I picture a younger me on this article because the long line of thiazide trials stretches back decades in time to when I looked just like the photograph. The large picture that heads this article depicts my spreadsheet of all of the trials I have reviewed, and this link will take you to that sheet. It is a nice place to go because it has links to each of the trials in case you want to take a look at them yourself. Of course the reason I am writing this article is the new trial by professor Fuster and his colleagues. You can see it as the last row in the table. Much larger than the rest, it is mixed. Those who … Continued


Long age, physicians gave calcium kidney stone formers oral phosphate supplements to reduce urine calcium and kidney stone production. But trials were small and informal, so when a single and excellent trial showed lack of benefit our generation left phosphate by the wayside. Science, however, has a way of correcting things. We now know that mutations in the gene encoding a kidney phosphate transporter (sodium phosphate cotransporter (NaPi) 2c (NaPi-2c) can lead to “idiopathic” hypercalciuria and stones as well as bone disease. The mutations reduce kidney ability to conserve phosphate. As a result, serum phosphate falls and multiple hormone signalers signal awry. Given this new knowledge, oral phosphate supplements seem an attractive treatment for special patients that a properly done kidney … Continued


Not rarely patients and readers on this site ask about vitamin D supplements and whether they raise the risk for kidney stones or reduce risk for bone fractures. This article is about the first question. In pursuit of the answer, I would like to share with you how one can come to know the ‘answer’.  It is not magic. Given modern access to PubMed many patients could come to a reasonable answer without me. The large image is of 25 hydroxy vitamin D (25D3). Liver cells make it from the vitamin D3 we buy OTC by adding the OH (hydroxyl) group at the 25 position (between the two ‘CH3s’ at the upper right. It is active on bone and GI … Continued


The painting by van Gogh, The Sower with Setting Sun (1888) Kroller – Muller Museum, Otterlo, Netherlands, has no obvious connection to this article unless you have read Nellie Hermann’s essay on the former mining district of Belgium called the Borinage. Writing in the Paris Review, she reminds us van Gogh lived there in the 1880’s amidst active coal mines now long obliterated. He based his painting on an earlier (1850) painting, The Sower by Jean-François Millet (1814–1875). The artist sold it in 1851 to William Morris Hunt (1824-1879), Boston, where in 1917 Quincy Adams Shaw, Jr. (who inherited it) and Mrs Marian Shaw Haughton donated it to the Boston Museum of Fine Arts where it resides. It seems unlikely van Gogh ever saw the original but … Continued

How To Count Kidney Stones

The aims of stone prevention are to reduce the number of new stones formed, and to reduce the growth of stones in kidneys by lowering supersaturation. This means we gauge our success by counting and measuring stones. Mostly, radiologists measure and we count. That is why I wrote this article. Ultimately, physicians are responsible for counting, but patients can help a lot. Moneylender and his Wife (Quentin Massys, 1465 – 1530), painted in 1514, hangs in the Musee du Louvre, Paris. Massys was ‘…the first important painter of the Antwerp school.’ How To Count New Stones New vs. Pre-existing A stone passed or removed or found in an image, and not present on a prior image, is a new stone. Therefore all … Continued


I put my youngest image here because the groundwork of what I offer belongs to 1965 when I first thought about the problem and 1968 when my paper about it was published. I should have put in as a bookend my latest and oldest image, too, for I completed the thought just last summer. The thought is about clearance, the very foundation of all renal physiology, and how I have always had it wrong, or perhaps better said, had an incomplete view of it. Probably most of us have done just fine with that incomplete view. But I mean to show you that traditional clearance and its practical uses are a limited version of what nature has to tell us. … Continued

How Plaque Forms

The white clouds you can easily see on this human papillum are Randall’s plaque, named for the man who first described them. Stones grow on them. You can find bits of plaque and on such stones where they were once attached. Because plaque forms in and lies in the renal papillary tissue itself, bits of plaque on stones often carry with them fragments of tubules.  This site has a long article detailing what we know about the facts of plaque, and rather than repeat it here is the link.  But how does this plaque come to be? Who Would Care? Scientists, of course. They measure things and imagine how they got the way they are. Then measure again to see if they … Continued

Kidney Stones, Stroke, and Myocardial Infarction

In other articles I have reviewed evidence associating kidney stones with high blood pressure and kidney disease. One might well extrapolate from these two associations that stone forming will also associate with vascular complications such as stroke and myocardial infarction. High blood pressure and kidney disease are well known risk factors for both. In fact, this is true. Forming stones associates with higher risk of both stroke and acute myocardial infarction (AMI) – commonly called heart attack – when compared to people free of stones. These associations do not say that stones themselves cause high blood pressure, or stroke, or AMI, merely that people who form them have higher risks of vascular disease leaving unsaid what might be the matrix of … Continued


I rarely write about new science in stone disease because this site aims mainly at patients and clinicians who want stone prevention now, not in some glittering and distant future. But this article is in the newspapers and promises – as if imminent – something far off and presently theoretical. It is lovely science, the pictures perfectly gorgeous, the promise wonderful to contemplate in a new and more elaborated world. But right now, it is just that – promise – so I have taken up my commonplace pen to make things clearer for those of us on the ground, struggling presently with what we have to do what we can do. The large photograph of the Cloaca Maxima is from … Continued


The title accurately reflects the pragmatic value of the new research I review here. This work shows, for the first time, how one can use urine supersaturation measurements as an estimate of kidney stone risk. It also tests more rigorously than any study to date the urine supersaturation hypothesis that places supersaturation in a position of high primacy in kidney stone formation. That test supports the primacy of supersaturation, and at the same time shows us how to use supersaturation as a graded risk factor, in the same way we use urine calcium, oxalate, citrate, and volume. I wish to thank Drs Gary Curhan (Harvard) and John Asplin (Litholink) for their careful review and corrections to this article. The beautiful … Continued

Other Kidney Stone Sites We Recommend

The web is majestic and grand, but filled with mixtures of good and bad reporting and advice. Here I have picked out of a simple Google search – kidney stones – some sites I can recommend. For these I try to make clear what I see in them as well as limitations. The featured site, though not ‘.edu’ is in fact a university level site run by distinguished experts and thoughtful patient advocates. It has a lot of patient content as well as medical materials, and the quality is very high. Dr Mike Nguyen,  Associate Professor of Clinical Urology at the Keck School of Medicine of USC in Los Angeles, CA, founded this site years ago and it has … Continued


This page has only one article because I have not been active enough in getting surgeons to write for us. It is very good, and covers a leading surgical modality. I need to get more of them. The Surgeon, David Teniers the Younger, Flemish, 1610 – 1690, hangs in the Chrysler Museum of Art, Norfolk Virginia. Ureteroscopy – An excellent review of this modern technique Percutaneous Nephrolithotomy – An equally excellent review of this complex stone surgery  

How Stones Form

This is a very long list as much of the site concerns this topic. I have separated the clinical materials from these articles except for a few obvious overlap areas. For example urine volume, calcium, oxalate, and citrate control supersaturation and the topic is here and in the lists of treatments and diagnostic findings. Because it is complex I have added headers for guidance. The photo shows kidney stones inside a kidney with Medullary Sponge Kidney. It is from our research laboratories.  Stones Themselves What kidney stones are – Very brief introduction Kidney stone overview – An excellent stroll through kidney stone land Kidney stone types – Detailed review of the minerals revealed by analysis of your stones Supersaturation What it is, how … Continued

Pain and Injury from Stones

This big topic includes the miseries of stone pain and the array of other diseases that constellate with stones either because stones cause them or because stones are part of a manifold of disease. Bone disease is common in kidney stone formers and often ascribed to idiopathic hypercalciuria or willful low calcium diet misused in stone prevention. But that bone disease may not be only from such causes but part of a larger complex. The engraving is just one of many one can find showing what stone removal was like – all bladder stones – in early times.  Pain and Injury from Stones Pain How do kidney stones cause pain? Kidney Injury Passing a stone: How Long Can You Wait? … Continued

Stones from Systemic Diseases

Here, stones are due to some serious systemic disease. We need to prevent them, but that invariably requires we cope with the disease that causes them. One could rightly say that uric acid stones fall in this category in that the low urine pH that drives them arises usually from obesity, diabetes, gout, or at least metabolic syndrome. But in all cases treatment devolves into simple increase of urine pH, and one does not cope with the underlying disease. Likewise for cystinuria. It arises from inherited transport abnormalities in the kidney proximal tubule. Once again, we cannot treat those abnormalities but only the final urine cystine concentration and therefore supersaturation. Even so, renal function tends to fall more in cystinuria … Continued

Fluids, Diet, and Meds for Common Stones

The most common kind of stone former has no systemic disease as a cause of stones – ‘idiopathic’ stone former means that. Being most common, their treatments rank highest for all physicians who treat stone formers. These articles include the treatment trials. This charming Kitchen Scene by Joachim Beuckelaer (1533 – 1573) is oil on wood panel and hangs in the Louvre.  Fluids Patient Q&A page about fluids – Underused; we answer questions How to drink enough water – Tips and day plans How to get a variety of fluids – Which fluids cause which prevent stones Fluid prescription for kidney stones – A serious article about how much you need Does water prevent stones; What’s your bet? – The water trial, evidence fluids work Web apps and smart … Continued

Testing, Evaluation, and Diagnosis

Every stone former needs fasting serum and 24 hour urine testing. Likewise important, kidney stone analysis and review of images – CT scans especially. Medical evaluation is what physicians do. They integrate the testing with the history of stones and everything that can promote stones in any one patient. Diagnosis is also what physicians do. It is the final synthesis and directs treatment. The lovely painting by Jan Steen (1625-1679) hangs in Apsley House, London. I have used it also for the page on systemic causes of stones because I like it a lot. Testing 24-Hour Urine Collections: Why and how – The basis for prevention, never omit them How to Use Urine Supersaturations – What a given value means in terms … Continued

Case 6: Bariatric Surgery and Kidney Injury

Bariatric surgeries can injure kidneys by raising urine oxalate excretion. This latter causes kidney stones, and raises risk of acute and chronic oxalate nephropathy. Overall, their benefits far outweigh these risks, especially when patients and physicians take proper precautions.But risk lurks as if in shadows, and waits on accident. The patient here inadvertently raised her risk of injury. Like all instances this one is just that: Opportunity to inspect the details of an undesired outcome so as to reduce the chance it will happen to others. The kidneys of anyone with increased urine oxalate excretion could be injured as her’s were, so common are the causes, so seemingly innocuous. The high resolution scan of a kidney from a child with primary hyperoxaluria … Continued


Watch the Video Gary Curhan and Eric Taylor have given us many insights into how diet might influence kidney stone risk. I think this new article by them and their colleagues a great opportunity for close reading and practical use of a high quality research paper remarkably germane to the practice of kidney stone prevention. What They Want We all know that science is about discovery that enables us to do something, or know how nature does something. As a consequence, most of us ask what kind of science a paper is about – doing or knowing. But we also all know that this dichotomy is false because almost every scientist is after at least some of both. Likewise, that a paper lies … Continued

How to Lower Blood Pressure in Kidney Stone Patients

Unfortunately producing stones means higher risk of hypertension and kidney disease. But most of the diet changes and even first line medications for stone prevention also lower blood pressure. Here is how that works. The featured painting, Vincent Van Gogh, The Starry Night. 1889. Oil on canvas hangs in The Museum of Modern Art, New York. Somehow, to me, the whorles of color bring blood pressure to mind. Some say the yellow halos about objects came from digitalis excess, from his physician. My Sources From time to time, quantitative scholars produce ‘guidelines’ about diagnosis and treatment of disease. Recently, a band of such have compiled results from the large literature on blood pressure treatment and given us this new compendium. For … Continued


Elsewhere we have described an innovative web based course aimed at reducing kidney stone risk factors via improved diet. Briefly, the course helps patients whose physicians have prescribed diet and fluid changes implement those changes, by teaching them to choose the right foods and fluids. We have articulated the underlying science of the kidney stone diet upon which the course is based. The powerful innovative element is that the course lives online, so it can present itself to patients via social media and websites, and patients can access it world wide. Likewise, costs can be very modest compared to conventional dietician visits because much of the work is group based and requires no fixed overhead for space. But however innovative it may … Continued


This may be the most important article – to me – I have written thus far. It is a plea and argument that stone patients need more from us than prevention of stones, because often enough they harbor significant diseases that associate with stone forming and require their own treatments. We need to treat the patients, not just their stones. The magnificent Garden of Earthly Delights (Hieronymus Bosch, 1450 – 1516) hangs in the Prado. I chose it here as it contains the whole world, which is to say that every patient is that self same. Stone Formers Have Other Disease Risks When you look at the data, kidney stones belong to a manifold of diseases that run together: Bone … Continued

Against Sugar

Gary Taubes has written a substantial and important book summarizing the evidence that table sugar is a toxin. In this article, from Aeon, Taubes summarizes his thoughts and marshals the evidence in a highly readable and convincing form. Briefly, he dismisses the older idea that sugar – through its calories – causes obesity that then causes diabetes and heart disease. Instead he brilliantly summarizes the evidence that sugar – fructose in table sugar, in fact – alters metabolism so as to cause insulin resistance and obesity together. Recently, in a far more plodding and regrettably long article I parsed through what I consider the most important evidence for what Taubes discusses: Recent trial work comparing fructose to glucose that shows … Continued

Consumer Reports Recommend Low Diet Sodium and Sugar

Multiple articles on this site point toward better health from reducing intakes of sodium and refined sugar. They are well referenced and well supported by scientific data. Recently Consumer Reports, an outstanding purveyor of unbiased information to US consumers has summarized contemporary scientific opinion in a more fluent and convincing way than I or Jill Harris could achieve. Their recommendations align with ours concerning sugar, and sodium. Likewise, they offer, as we do, tips on how to read often misleading package labels. Being a popular magazine they do not consider bone effects of sodium, as we do, nor – of course – our unique issues about kidney stones. Even so, they have put their weight and reputation on the scale … Continued

Kidney Stones, Kidney Function, Kidney Disease

Glomerular filtration is the main life sustaining kidney function, and kidney stones can cause enough damage to lower it. Usually the reduction is very modest, but sometimes stones can cause kidney failure. This means, like all diseases, stones are best prevented as early and as completely as possible. This ‘just the facts’ version tells about what filtration is, how physicians measure it, how much kidney stones lower it, and how often that occurs. Two longer articles give the details. One is comprehensive. The other focuses on only kidney disease, but is long. Much of this text is redacted from the other two articles. I left out pictures, data, and links to PubMed to emphasize the main points. The featured painting is … Continued

Kidney Stones Can Cause Kidney Disease

The first article in this series of three summarizes the importance of filtration, the rudiments of how we measure it, and the results of research concerning how kidney stones reduce it. This article gives the details of kidney function in stone formers. It carries the key references, and supports the summary assertions of the much shorter precis. But because it does not duplicate the brief introduction to filtration per se, I advise reading the shorter first article as an introduction. The third article tells how filtration works, and the details of its measurement in patients including the eGFR estimating equations. It illustrates how filtration affects key stone risk factors and offers a brief tour through the kidney for those who … Continued

Glomerular Filtration

Kidney stones form at the tips of the renal papilla, and what forms them is the functions of the kidneys as driven by the needs of systemic homeostasis – maintenance of constant and normal blood levels despite wide variations in intakes. Stones themselves, obstruction from their passage, and consequences of infection and surgery all can damage kidneys. Multiple studies have linked stone forming with kidney disease, usually mild but sometimes serious. Kidney disease is detected mainly by tests of glomerular filtration. Even more, the very formation of stones depends in a way on the high filtration and subsequent reabsorption of critical materials like calcium. Given this anyone with kidney stones needs to know what filtration is, how physicians measure it, … Continued

Randall’s Plaque

This is our main article on Randall’s plaque, a papillary nidus that fosters growth of calcium stones. Other articles on this site illustrate plaque, and discuss plaque as a mechanism of calcium kidney stone production. But these have used plaque as part of explanations for stones not as something in itself. This article provides a full narrative about modern plaque research. Because our own research group performed much of the modern work we may seem perhaps partisan. But in fairness we do show what others have contributed. A word about context. From long before our time to now, scientists have recognized the massive numerical predominance of idiopathic calcium oxalate stone disease as contrasted with stones arising from systemic disease. Our concern here … Continued

Sugar: The End of Our Love Affair

We love it. As a people Americans eat 66 pounds of added sugar a year per person. Each one of us eat that much added sugar. Yes, that much table sugar, sucrose, the bad stuff. It may be bad but I love it, passionately, and with the fondness only time can add to a relationship. Frankly, only the writing of this site put me on to the dangers of excess added sugar. A physician all of my adult years yet blithe enough about added sugar I knew its main drawback as mere obesity. Now I know better and plan to leave it be and live my life without its company. The pretty graph at the right comes from the US … Continued

Mechanisms Causing Uric Acid Stones

My book chapter makes the prime point that low urine pH causes uric acid to crystallize in urine and produce kidney stones. But it does not detail what lowers urine pH to such an extreme. In part, bowel diseases lower urine pH. That is another subject altogether, because they also cause calcium stones. So they need their own articles. But in the main, low pH arises in people who are obese, have metabolic syndrome, diabetes, vascular disease all in some combinations. As an alternative,sometimes low pH associates with gout and none of these are present. In either case, this article concerns what kidneys do to lower pH in the absence of an obvious systemic cause. This article parses out and pulls … Continued

Case 5: Severe Hyperoxaluria

Severe hyperoxaluria – always worrisome, never something to dismiss or even wait a long time thinking about. The Vegetable Seller’ by Flemish painter Joachim Beuckelaer (c.1534-1574) seems a perfect image for this exercise in vegetable excess. He was never very famous but influential concerning food and kitchen scenes.  Jill Harris (pictured right) co-authored this article with me.  Kidney Stone History This 47 year old woman had her first manifest stone 12 years before I first met her. It was removed by SWL. The second stone was about 6 years ago treated with URS. Stones were 90% calcium oxalate monohydrate, 5% calcium oxalate dihydrate and 5% calcium phosphate. Three years ago, and then one year ago, more stones were reported in her … Continued

Chapter One: Personalized Kidney Stone Prevention

A Good Place to Start VIDEO 1: RISK FACTORS (17 min). VIDEO 2: EVALUATION (13 min) AND TREATMENT (13 min). The videos review the chapter and emphasize the main points. I would start with them. Salt Ponds The featured image shows salt harvesting from evaporation ponds. The sea is salty and like our blood holds its salts in solution. But if you channel the sea into ponds, and balance things so the sun evaporates water faster than new water can enter, the remaining water overloads with sodium chloride. It crystallizes out of solution as sea salt. Workers collect it for us to season our food with. Is it not an apt picture? Our Blood is the Sea, our Kidneys Make the … Continued

Chapter Two: How Kidney Stones Form

Watch the Video The video is a big enhancement of this article, I recommend it. The Structure of Kidneys Stones form inside the kidneys and the urine collecting system. How they form matters to patients because surgeons can see formation sites during stone removal by ureteroscopy or percutaneous nephrolithotomy. The amount of such sites gives a clue as to future stone risk and also to possible damage done from crystal deposits in kidney tissue. We cannot discuss where stones form unless you know how kidneys are constructed. If you already know this, move on. But if you do not let’s stop here and review how kidneys are put together.  The linked article is long, so focus only on the cutaway … Continued

Chapter Three: Coping With Confusion

Among the thousands of comments on this site, this one theme rings out. Patients Are Confused Many patients just have no idea about what to do. They suffer from confusion. They have stones, one or many. Surgeries occur, or not. CT scans show this number of stones, or that number. Physicians may say contradictory things, or things that seem contradictory. And all the while new stones may form, more pain attacks may come, and lay to waste life otherwise spent in pursuit of work and family happiness. As a way out, people seek remedies, on the web, from friends, from physicians, of course, and often they do not work. Or, they do work but seem not to. The painting, Taking the Census, by Francis William … Continued

Science and Kidney Stone Prevention

Why Science Matters DRAFT – NOT COMPLETE AT THIS POINT What Am I Writing About? About medicine, all we know of any practical consequence more than what was said in Babylon comes from science as practiced in the West since Harvey and Galileo. And, of all topics in medicine, my rather global and presently unsupported assertion applies remarkably to our common project here, the prevention of kidney stones. To say this more exactly, rational, modern, effective kidney stone prevention arises naturally from knowing what crystals make kidney stones and what forces drive such crystals to form. Prevention arises from cause, cause from science. Why Am I Writing This? Few would doubt that science drives medical progress, so why have I … Continued

Chapter Four: Who Are You?

Phenotype is a medical term physicians use to identify groups of patients who share diagnoses and treatments in common. Although every kidney stone former has unique traits that need attention, they can be grouped into phenotypes for which certain general treatment approaches have been tried and found valuable. Within those general approaches refined treatment answers to those unique details particular to a given patient. Your Name When successful, the process of this chapter grants you a name. That name sums up where you fit in as a type of patient. Because patients within a given type have in common causes of stones, treatments and trials, and long term outlooks – so called prognoses you want to know where you fit in. That name is the name … Continued

Chapter Five: Idiopathic Calcium Stones

You have idiopathic calcium stones. That means much of this site applies to you and your disorder. But the many articles read without a guide or sequence can confuse. You would be best off reading here, and following links as they come up. Of course you are free to browse as you like, but if you want a guide, I am here. Pieter Brueghel II (The Younger) A Village Fair (Village festival in Honour of Saint Hubert and Saint Anthony) 1564/1638 (Mackelvie Trust Collection, Auckland Art Gallery Toi o Tāmaki, purchased 1961) shows a crowd, which is appropriate for this most common kind of stone former.  Begin Here You should not use this chapter unless you have come to it by the right … Continued

Chapter Six: Why Delay Prevention?

I often hear physicians say, ‘Of course, a lot of my patients had only one stone, so I just tell them to drink a lot of water.’ I don’t criticise them for saying it or doing it. They follow standard practice. The defects lie in those of us who study the data and fail to make ourselves useful by making ourselves clear. Let me be clear, then. Ideally, prevention should start before the first stone. The Image, Jan Steen, Couple in a Bedroom, 1665-1675 seems to convey the idea of ‘Why Wait’. Water is Great Water as a treatment is spectacular. It undoes the very process of renal water conservation that creates supersaturation. And let’s be clear. Supersaturation is the beginning … Continued

Chapter Seven: Primary Hyperparathyroidism

Watch the Video In my very long and complicated article I detailed primary hyperparathyroidism (PHPT) like a good scientist should. With all my heart I tried to make it plain enough for people in general to get a sense of how things work, but looking back on it, I doubt many will. Anyway, this book structure makes a place for summary and synthesis. Is this PHPT lite? Not really. It is PHPT practical, devoid of all but assets material to evaluation and treatment. Even so, in those areas I go into perhaps greater depth than in the parent article. The two articles complement each other as best I can arrange. Alabama Grist Mill Dam by Beverly Hammond catches the sense of how … Continued


Primary hyperparathyroidism (PHPT) is a systemic disease caused by an excess of parathyroid hormone secretion. It causes calcium kidney stones but also multiple other abnormalities, especially of bone. Here, I am concerned with that subset of PHPT patients with kidney stones. A Curable Cause of Kidney Stones Unlike most stone formers those with PHPT have a good chance at permanent cure. This makes detection of PHPT a paramount aim for patients and their physicians. As I shall tell you, PHPT raises serum calcium above normal and is detected from blood test results. The elevation of serum calcium can be slight and variable so patience and persistence matter a lot. Once diagnosed, PHPT can be cured by a surgery that modern … Continued

Chapter Eight: Uric Acid Stones

Uric acid stones, to me, means not just pure uric acid stones but any uric acid in stones. If this seems fey, let me explain. Uric acid is a peculiar kind of crystal. Low urine pH causes them and treatment that raise urine pH prevent them altogether. Whether they form combined with calcium stones or pure, treatment is the same. Why then scruple over percentages? If I find uric acid in any stone, I look at urine pH with a yellow eye. Should it be low I treat it surely and on the moment so at least that crystal be banished forever. The Profligate Punished by Neglect, Edward Penny 1774 catches the common motif of diet excess, obesity, diabetes, and … Continued

Supersaturations Match Kidney Stones

This is a story about how well the supersaturations we measure in 24 hour urines reflect the average supersaturation in the kidneys of patients, whether supersaturations match kidney stones – match the crystals stone contain. If they do match well, we can trust supersaturations as our guide to treatment. If stones and supersaturations do not match well, what value can supersaturation measurements have? They could mean nothing. Stones form over months or even years. Can a few frames tell us about a movie? It is also a story about my own past because Joan Parks and I did the work over 20 years ago. Though old, human observational data do not go out of date. The stones and 24 hour urines from those patients … Continued


Our newest venture – the Kidney Stone Prevention Course. It arose from this idea: Kidney stone prevention depends a lot on proper diet and fluids, which patients control. This site tells people what that diet and what those fluids should be, but not how to eat that diet or drink those fluids in real life. They have to learn how. So we built the kidney stone prevention course to help them learn. Just as Raphael imagined generations of brilliant minds come alive together in The School of Athens (Raphael, 1509 -1511; Apostolic Palace in the Vatican.), we – on a vastly lower plane of existence – imagined and have, in the kidney stone prevention course actuated the knowledge on this site into real life.  … Continued


Do you need a low oxalate diet? Who does? Who does not? How can you tell? I chose the gorgeous painting by Raphael that hangs in the Musée Condé Chantilly because three surpasses one. VIDEO FOR THE ARTICLE Who Needs Low Oxalate Diet? Most of all, those whose stones contain calcium oxalate crystals and urine oxalate enough to promote such stones. Less so those with systemic diseases – bowel disease, malabsorption syndrome, bariatric surgery, and primary hyperoxaluria – that raise urine oxalate. Their diseases require many treatments, only one of them low oxalate diet. Therefore, I write here for only patients without a systemic cause of stones. Do Your Stones Contain Calcium Oxalate? If your stones contain little or no calcium oxalate crystals, and urine oxalate itself poses no danger to … Continued


The old fashioned intravenous pyelogram pictured in the header of this article depicts the normal left kidney of an 18 year old woman, and her severely obstructed right kidney – from a stone. That kidney has lost some of its tissue. In his review of stone pain, Mike Borofsky showed that obstructing the kidney of an animal reduces its function and provokes inflammation. Obstructing stones affect human kidneys similarly, and can damage them, but we know fewer details. Fortunately, kidneys seem resilient enough that most stone formers maintain reasonable kidney function. But stone formation not rarely leads to kidney disease. Though often mild, in some cases losses can be severe, even to kidney failure. What do we know about the … Continued


Would anyone bet against water to prevent stones? Here is the first of new articles that highlight stone treatments in a simple format. These new articles were provoked by what patients asked for, and by Freakonomics. Because patients asked for clear answers about treatments, I lifted ‘water’ out of my long article on treatment of calcium stone formers, and simplified the style so the main points stand out. I also suggest betting, something we all understand. Freakonomics offers a three part podcast about the woeful state of medicine. Doctors, they say, rely on received wisdom, poor clinical trial design, and bad data. At the end I ask you to vote if we kidney stone physicians suffer from these three defects, and by how much. Voting sharpens the mind, or should. … Continued


My Question Tell me what you want next on this site; that is my question. I have been writing this site – with the able help of my co-authors – since July 2014, and have reached what I might call a kind of plateau. Much of what I came to say about the most common kinds of kidney stone patients is said. Because the main work is done for the moment I have come with my question to you. The readership of the site has grown from 50 people in the first month to a present running average of 55,000 – 65,000 people monthly, depending on the season, and many of the visitors read quite a bit each. People find the site valuable, … Continued


It was a comment by Dr. Robert Perlman, a friend and brilliant scientist in the field of evolutionary medicine, that set me off on what I can only call a historical and scientific pilgrimage, a pilgrimage to the beginnings of the modern guidelines. At the end of my most recent article on the guidelines and our present stone fomenting diet, he pointed out that the US diet guidelines are so influential and the new ones so helpful in management of kidney stone disease we all must question who creates them, and how. The guidelines must have, he implies, the kind of elaborate and winding history one expects from a succession of governmental committees which, howsoever well served by volunteer scientific experts, can be subverted – by money, by … Continued


I have summarized the scientific evidence that low intakes of diet calcium and potassium and high intakes of refined sugar and sodium and protein raise risk of stones and loss of bone mineral. I have pointed out that the recommended US diet specifically seeks to correct all five of these risks and we should recommend it to all of our stone patients unless contraindicated by some specific problem. But I have not as yet shown to what extent we as a nation eat a diet deficient in calcium and potassium and excessive in refined sugar, sodium, and protein. In other words I have not as yet quantified the extent of the problem that stone forming patients face. Here is evidence from a large body … Continued


A Remarkable Concordance From 1980 to now the US government has published diet recommendations for the American people. Gradually and over time these have become quantitative and specify amounts of critical nutrients such as calcium, sodium, refined sugar, protein, and potassium – as alkaline anions in mainly fruits and vegetables. The goals are reduction of osteoporosis, hypertension, obesity, and diabetes. I shall call this the Ideal US Diet. Surprisingly, though aimed at stone prevention and management of bone disease from idiopathic hypercalciuria, decades of kidney stone research have identified precisely the same diet. Even more surprising, the Diet Against Systolic Hypertension (DASH) diet resembles the current Recommended US Diet, and stone researchers have found a reduced risk of stone disease in people who eat ‘DASH – … Continued


Medullary sponge kidney (MSK) is more spoken about than witnessed, and more witnessed than accurately diagnosed. This patient adds to the 12 we have described in our publication, and adds also in having a very long and evolving history with one of us (FLC). We write for a general audience yet hope to include a level of detail that satisfies physicians and scientists. Here, we may fail of clarity to the one audience or of a sufficiency to the other because the disease is complex. But withal, the evolution of diagnosis and care for this person so educates and the surgical anatomy and histopathology so instructs we have chosen to share the experience. What is it we are sharing? MSK is a Unique Disease MSK is remarkably specific in … Continued


Recently we presented what we think of as The kidney stone diet, meaning a unitary diet platform suitable for idiopathic calcium stone formers in otherwise good health. The story of that diet and the implications it has for stone prevention deserve perhaps a bit more commentary than we allowed for in the original article. The lovely image – Hendrick van Cleef, The Building of the Tower of Babel hangs in the Kröller-Müller Museum. He (1525 – 1589) is one of a family of famous painters and much admired for his brilliant textures and colors. Babel was to keep us aware we are divine. The Narrow Winding Path Over many decades, kidney stone researchers have gradually recognized what the ideal kidney stone diet might be. They did … Continued


If we put together everything on this site about diet for kidney stone prevention we get a reasonable and consistent image of one basic pattern. It is more or less what is ideal for idiopathic hypercalciuria and for reducing urine oxalate. It is the diet that has been used in the one major trial of diet for stone prevention. It accords with modern recommendations for the health of the American people. More or less, after all is said, there is only one diet plan that meets the needs for kidney stone prevention and we have called it ‘The Kidney Stone Diet.’ ‘We’ are me and Jill Harris (pictured right). Of course, we are speaking of the diet for treatment of idiopathic calcium stones. … Continued

Case 3: A Success Story

This is a first for the site, and perhaps it should have been a feature long ago. After all the generalizations and reviews there is something wonderful about a single instance that contains all the elements of a topic in the kind of instructive detail we can get only in life itself. Pat – who has permitted me to use his name and data – forms calcium stones and has idiopathic hypercalciuria and a job that makes hydration a problem. For treatment I wanted to use low sodium diet to lower his urine calcium excretion and if possible avoid thiazide diuretics just because of his job which is outside and in summertime poses serious heat loads. MIchelle, his wife, created a reliable low sodium diet for him as proven by multiple follow up tests and that reduction of sodium lowered urine sodium and stone risk, as one might expect. I asked her to share her experience in doing this, and she responded with this wonderful article. It helps that she is a professional writer! I am indebted to Michelle and Pat for their story, and I hope you like it. 

Does Too Much Protein Increase Stones or Damage Bones?

Some of us overdo things with shakes and powders, some with 2 pound steaks. Others love sweets too much and don’t eat much protein. Like all the diet factors in stone and bone disease, protein intake is complex. Certainly, we all need protein in our diet but how much? Experts debate the best course, and patients wonder what to do. Abraham van Beijeren was, by the way, little recognized in his day but now considered a major painter of ‘luxuries’ like this standing roast. I chose it, as opposed to others more brilliant, because it looks  modern – I have seen something like it on my own dining room table. In preparing this article I have made considerable use of the analyses performed by professor … Continued


Here are all the trials for prevention of idiopathic calcium stones, and my personal approach to using their results in clinical stone prevention. The whole site thus far has been built to support this article, which is the capstone of the enterprise. To highlight its importance I have made it header type larger.

Beside the usual references, I provide spreadsheets that contain all of the trial stone data with links to the original articles and PDF images of the articles. I also provide spreadsheets of stone risk data from the trials that I use in my analysis of the physiological responses to treatment. So this is a definitive as I can make it. I have left the two preceding videos in red because they are the steps up to this article, and perhaps people might want to view them in preparation. The two prior articles on phenotypes that come before the videos are also preparatory to this final presentation.

I say final because with the full presentation of all of the trials we have more or less covered the entirety of idiopathic calcium stone disease and need to move on to other stone types and to the systemic diseases that cause stones.

Video Article: How Stones Form

With considerable trepidation, I unfurl my first and certainly very unpolished video offering. The good part of the articles on this site is their devotion to scientific accuracy and referencing from PubMed. The bad parts are their opacity, length, and difficulty. I have long been a public lecturer and decided that video offerings might be a valuable add on. There is more room, I think I speak better than I write, and it seems to me one video can summarize and complement a group of written articles, so I did this one. It covers crystal formation, how crystals are made, and where in the niches and crevasses of the kidney they actually form. Its message is my usual one: Prevent crystals and you prevent stone disease. This is a beta version. I know it has some errors in it. I also know it lacks refinements I need. But, refinements and corrections will come. Let me know.


Here is the most common kind of stone former, described in such detail as one can muster up at this time. They are simple to diagnose: Stones containing a preponderance of calcium oxalate, no uric acid, struvite, cystine, brushite, drugs, or rare organic materials, and exclusion of any systemic disease as a cause of stones. More or less, these patients are stone disease as it is seen in primary care and most urology practices. Of the millions of stone formers most are like this. The trials for prevention of calcium stones have mainly used these patients as a majority of subjects. However common they may be, and easy to define, they are complex in the way that they make stones, and it appears that there may be not one but perhaps two kinds of idiopathic calcium oxalate stone former. Because of modern flexible ureteroscopy the types of idiopathic calcium oxalate stone former will soon be told apart during stone removal surgery, and patients and their physicians confronted with a variety they may not fully expect. This article sums up what is known, as best as I can manage.

CASE 2: A Calcium Oxalate Stone Former

CLINICAL FINDINGS A man in his fifties formed his first stone in the early 2000’s and his last 6 months ago. There was a single passage event a year or two after the first stone at which time he was given hydrochlorothiazide 25 mg daily. A right SWL procedure was performed 1.5 years ago because of a stone attack, and  potassium citrate 10 mEq twice daily was added in treatment. A right sided URS procedure was performed 8 months later but was not completed because of bleeding. A right URS 6 months ago is said to have left his right kidney stone free, but some stones were seen on the left. I did not have images to review when I saw him. He believes that all of … Continued

CASE 1: A stone Former

CASE 1: A Stone Former. As you will see, this is a person with considerable numbers of stone attacks who has certainly produced large stones in the past, but he posed major problems in deciding if stones were active and is therefore a perfect place to start. His many laboratory abnormalities are just wonderful for thinking about stone pathophysiology.


The second in this series of stone forming phenotypes, the calcium phosphate stone formers are less numerous than the calcium oxalate stone formers, but perhaps more worrisome, and certainly more complex. There are two types, those whose stones contain any brushite – an unusual form of calcium phosphate in stones, and those whose phosphate is only hydroxyapatite – the mineral found in bones. This latter group is to a large extent composed of young women, for reasons we do not know. Phosphate stones are likely than the calcium oxalate variety to be numerous, and often produce nephrocalcinosis, a mixture of small stones and tissue calcium deposits. Nephrocalcinosis, in turn, is often labelled medullary sponge kidney simply on radiological grounds, even when the distinctive lesions of MSK are not necessarily present. Likewise, phosphate stone patients can appear to have renal tubular acidosis because of nephrocalcinosis and because RTA and phosphate stone patients both produce a more alkaline urine than do normals, or patients with calcium oxalate stones. All in all, this is a complex form of calcium stones, challenging for clinicians and often very trying and concerning for patients with it. The article is long and difficult, so you might want to watch this video by way of an introduction.

Video article: Supersaturation – The calcium crystals

As I see things, all of stone disease concerns the balance between the opposing forces of supersaturation and kinetic retardation of crystallization. The former is better understood and more tractable because easily measured and commercially produced for clinical care. The latter is not fully understood in term of the molecules responsible and not commercially available as a clinical test. So of the two primary forces that control whether crystals can form, we have only supersaturation to use. Being so central, this one measurement, for each of the stone crystals, has unusual importance. These three relatively short videos cover the main elements of supersaturation: What it is, how kidneys produce it, and how it is measured and used in stone prevention. They combine with ‘How Stones Form’ to make what I think is a fine story about stone disease and a fine basis for understanding how stones are best prevented. I have gathered together in the article links to all of the supersaturation articles on the site thus far.

Web Apps and Smart Bottles

This is an article that can be written only by the readers of this site. We are not product testers nor do we do market surveys. But given how many fluid and diet apps one can find on the web and also given how many people come to this site every month we should be able to get a good idea about which ones seem of value. The benefit of accumulating your experience in comments to this very brief article accrues to all of you who come here. Whether you use an app or not crowd sourcing of a kind can tell us all which ones seem really good, and we can all use that knowledge. There are almost no words in the article, but as the results come in – in other words if you will share – we will count up by app in a table or so, ongoing. As for smart bottles, there are only a few on the market, but we should be able to get an idea about them if you will share. So, here it is: A blank slate for everyone to write on so everyone can benefit. Please share.

Control of Urine Oxalate Excretion

There is no doubt that urine oxalate excretion is an important factor in calcium oxalate kidney stone production, and that excretion is a very complex outcome of transport in the gut and kidney tubules and, of course, diet calcium intake. We have devoted a lot of energy to refining food oxalate lists and making a reasonable diet plan for oxalate. Here, we have taken on the harder task of reviewing the complex movements of oxalate from food into urine. The intestines not only absorb oxalate from food into the blood, they can secrete oxalate back out from blood into the gut lumen from which it is removed in the stool. The kidneys remove the net of diet oxalate absorbed minus that secreted by a process of filtration and subsequent renal cell reabsorption and secretion of that filtered oxalate. It is as though evolution has handled oxalate like a real hot potato: keep control of how much oxalate the kidneys need to remove and keep control of the blood oxalate concentration. This seems prudent – if one dares to speak this way about evolution – as oxalate can crystallize in blood as it does in urine and both processes can be dangerous. The new work on oxalate transport does not now directly translate into new tests or treatments for patients, but surely will. So I and my brilliant colleague Dr Hatim Hassan – who is the real expert here – have written about the future in medicine. Because the article is very complex and may not get a lot of readers – scared off – I have made a tiny movie to introduce it by way of encouragement. 

My Lab Report

This little goodie started with my partner Dr Anna Zisman who to wanted us to have a simpler format for patients to follow in looking at their 24 hour urine lab reports. Answer five easy questions and get back a list of what you have to do with fluids and diet. Try it. Let me know if it works. If not, can you help make it better?


Well, here it is, the last pillar in the foundation. My goal is to enable patients to achieve successful stone prevention and I believe this requires a partnership with their physicians, a partnership in which they play a very active individual role. Patients after all are the ones who can manage diet, fluid intake, and life demands, only they can assure that 24 hour urine collections are representative of normal life, and, frankly, only they can decide on a life of long term prevention. Stones being rarely fatal and usually not a cause of progressive kidney disease, patients can elect prevention or not, and their physicians are in a role more like attorneys and accountants than authoritarian directors of events. But as in Eden, one can expect proper choices only if one has provided full knowledge, which I have set out to accomplish. By proper I mean most suitable to patients given full knowledge, for some may not care to exercise themselves so much as I think they must to be successful, whereas others may consider the work of prevention slight indeed compared to the consequences of continued stones. In any event, this article is the end of that cycle of enablement I can manage, and I put it here, as in all writings, as the chef puts out her best effort – to face the indifferent judgement of the gourmet.


These two articles cover the main stone types, and this new one on uric acid parallels the prior one on calcium stones. Like the calcium stone article it is meant for patients, although physicians might like some of the nuances. The purpose is not to make patients into their own physicians but to enable them to understand their own stone forming abnormalities. My ruling hypothesis is that patients want prevention, and will embrace and implement the changes needed with more enthusiasm and endurance if they fully understand the goals. LIkewise if they can themselves follow the effects of their efforts on stone risk factors they will believe that what they are doing has real meaning. I know that hypotheses are for disproving, and I know someone may well do a prospective double blind randomized trial, some day, to test mine. Right now, I believe in the idea because of Eden whose resident twosome were not just told about the tree but exactly why they should not eat of its fruit. I know it is an unfortunate comparison, given the outcome, but much effort was expended on education. My source for the details, apart from the Hebrew Bible, is Milton, J: Paradise Lost; Books V – Viii.


This site is meant to promote prevention and my current hypothesis is that enabling patients to read their own 24 hour urine tests with a professional eye will help achieve that aim. It is not an easy task. Lab reports, even the best of them, are dazzling arrays of numbers in often mysterious units. Even physicians have some work to do. But numbers are numbers and people can read them if they have the code. Here I have parsed out the main numbers for the calcium stones: Volume, calcium, oxalate, sodium, citrate and pH. Because this is the first article on reading this kind of report I also discuss collection quality, conversion of units – some labs report, as an example, calcium in mg/24 hour, others in mmol/24 hour, even mEq. So I introduce the simple conversions needed to use what I have written for a report with different units. Likewise I introduce how urine creatinine can be used to estimate collection quality. The supersaturation come at the end, as they should, being the final summary of everything. The tone is about that for trainees in nephrology or urology I have often worked with but with jargon elided and a focus on lab results per se. Those interested can follow the links into the thickets of the site which hold enough to satisfy most appetites. The main purpose is to enable patients to cast a cold eye on their own problems and on the results of treatment efforts so that in the event saturations can be effectively reduced and stone recurrence with them.


The thiazide type diuretics are able to reduce new stone formation and are an important part of stone prevention regimens. Here is all about these drugs: The trials that show they work; How they work; What they do for bone: Certain precautions in their use. To give a pill to someone is to throw a seed on unprepared ground – it is a sterile and doomed enterprise. All the features of prevention from diet and fluids and lifestyle come first, so that what one can do with them is being done. Then the drug will be most useful. And, you will know by the fall in urine supersaturation achieved. Whatever it was when stones were forming is too high, and real treatment means it has been reduced. After all that can be done without thiazide has been done, there will no doubt be residual supersaturation lowering needed, or one would not use the drug. The marginal benefit of the pill can be assessed by the extra fall in supersaturation it produces. Which supersaturations? Those related to crystals in the stones forming.

Five Steps to Stone Prevention


Ultimately we want to prevent kidney stones. Trial data, and my own large experience correspond in this one point: Prevention is a reasonable objective that can be successfully accomplished. Here is my own approach, simplified into five steps. They correspond to the overarching theme of this entire site: Stones require crystals; crystals follow the laws of physics; the force that drives crystallization is supersaturation; commercial vendors in the US provide supersaturation measurements in 24 hour urines at a reasonable price. So the steps are indeed simple: Know the stone crystals; measure the urine supersaturations; lower those urine supersaturations for the crystals in the stones being formed; keep them low. If stones persist, lower them more. It takes physicians to initiate this process, and there are complications such as the occasional systemic diseases which must be detected and treated in special ways. But it takes motivated patients to carry out the long term changes in fluids, diet, lifestyle needed, and to take the medications provided. It is time to focus here: Prevention is better than surgery. To help, I wrote a companion article several months ago about how to organize your medical stone prevention visits so as to get the most out of them. 

Control Your Salt for Fewer Stones and Stronger Bones

Two good trials support lower sodium diets as a way of reducing new calcium stone formation and of protecting bones from calcium loss. The physiology behind these trials is detailed in the articles on idiopathic hypercalciuria and salt. In Italy at least, and in men with calcium stones and idiopathic hypercalciuria, a diet low in sodium, moderate in protein, and high in calcium leads to less stones than low calcium diet alone, and in fact to a rather low new stone recurrence rate. Among postmenopausal women, a high calcium low sodium diet brings bone mineral balance into the positive range: Bones add mineral. Neither trial is comprehensive in covering men and women, young and old, US vs. Italian cuisine, but they are the only ones we have of this quality, they are consistent with the science we have, and convincing. To me they are enough to recommend low sodium diet, moderation of diet protein, and high diet calcium for calcium stone formers with idiopathic hypercalciuria, recommend this kind of diet without reservation pending what I hope will be more trials which cover a wider range of patients and of ages. It is this kind of additional trial we really need in the US right now, substantial, bearing on really important diet interventions, and arising out of a sound scientific base.


It has always seemed to me that medical practice is a dance. One leads, perhaps, but the other does, too. If physicians know more steps, patients can prepare their parts in advance and organize their large roles in long term treatments so the final result is graceful and ultimately elegant in obtaining the best results with the least extra effort and resources. After all, it is patients who know the past and will determine the future. Here are lists for you, ways to think about time with physicians, and especially a way to think about your treatment over the long years of stone prevention. For it is years, this being a chronic and recurrent disease, years of work by you with only a rare burst of medical guidance here and there. Yet so important as rare needs preparation and curating so what transpires is not lost. What is here is my own ideal of how things should happen, how the dance is conducted – so brief, so important.


Idiopathic hypercalciuria may well be the most complex and important issue in all of medical management of calcium kidney stones. It arises within the elaborate systems that regulate calcium metabolism and produces both a risk of stone formation and of bone disease with fractures. IH is strongly familial, almost certainly genetic in origin, and present in children as well as adults. Treatments used include high calcium – moderate protein – reduced sodium diet, moderation of dietary sugar loads, and potassium citrate, and thiazide type diuretics, each of which act through different and reasonably well characterized pathways which cannot be understood without a knowledge of how IH works in the first place. Unlike stones themselves, supersaturation, or citrate, each a very large and important topic, IH cannot be presented well – at least by me – in separated linked articles but only in one article that carries its many intersecting physiologies along side by side and uninterrupted. Being a long and comprehensive article, foundational for this site and – to me at least – for comprehension of the whole topic of pathogenesis and treatment of nephrolithiasis, this article is not necessarily meant to be read all at once but rather used as a resource. I will cover the treatments of IH later on, in separate articles.


This is a foundational article for the site. High rates of urine calcium excretion (hypercalciuria) will raise calcium concentration at any given urine flow rate, and therefore raise supersaturation with the calcium stone forming salts. Genetic (‘idiopathic’) hypercalciuria, simply the upper end of the normal range, is greatly over-represented among stone formers, and idiopathic hypercalciuria (IH) is a main focus of treatment for stone prevention. As well, people with IH, stone formers or not, are at risk for bone disease. This article introduces hypercalciuria: IH itself and a few of the less uncommon named diseases that cause hypercalciuria like primary hyperparathyroidism, renal tubular acidosis, and sarcoidosis. It mentions confusing disorders such as normocalcemic primary hyperparathyroidism, secondary hyperparathyroidism, and familial hypocalciuric hypercalcemia. It also offers evidence linking specific levels of urine calcium excretion to risk of stones, a very important matter in deciding what needs to be treated.


Being so important, the very force that drives crystal and stone formation, supersaturation has enjoyed considerable attention on this site and it seemed time to gather the articles about it into a coherent narrative. The walking tour seems apropos as such tours visit a group of related sites and have, or should have, a guide to put each one into perspective and extract from the entire group some large and generous idea about the world from which they arose. My prior one on stones themselves attempted the same.


Given that kidneys supersaturate the urine by conserving water, no treatment can be more immediate and direct than to drink more water than one needs so the kidneys can excrete it and in the process dilute the urine salts – which is to lower supersaturation. Alas, there are many patients who cannot or will not drink enough water, and it is these Joan Parks writes about in this article. Over our 40 years of collaboration very many patients with the problem of persistent low flow have come through our stone program at UC, but Joan and I never wrote a paper about them so much of what we found is buried in their charts. By way of redress, Joan has conjured up a lot of details that we think people will find valuable, even though they have not been shaped into the formal character of a scientific paper.


Not a few of you have heard this word and wondered what it meant for your health and management. Here is what it means. On the one hand, crystal deposits in kidney tissue. On the other, the name radiologists use when they see calcified regions overlying your kidneys, regions that are not clearly free stones but could be stones or tissue mineral. They really cannot tell with great precision. They never could. Modern high resolution ureteroscopy can tell, and surgeons everywhere have adopted this wonderful technology into common practice. You need to know this. Those of you who carry the diagnosis of nephrocalcinosis will all benefit from modern surgical visualization as opposed to indirect means of radiology.


If you want a comprehensive view of what kidney stones are and how they are made, I have put together various of the articles in this by now rather large site to make up a kind of story, or narrative, or, as I like to think of it, a walking tour. Read in the order I suggest, and take a look at the few narrator comments and I promise a nice overview of the topic. More will come if people seem to like this format.


Dr. David Goldfarb has taken on the American College of Physicians concerning the flawed guidelines they have promulgated for prevention of kidney stones. I have criticised these guidelines  – for fluids and medication use – in two prior articles. My criticisms were about their intellectual failings and naivete concerning medical practice. His are broader because in addition to their intellectual and medical flaws they were published against the advice he gave as a peer reviewer of the articles. Furthermore, as he points out, they do not properly acknowledge the guidelines of the American Urological Association, which represents the main body of physicians who actually take care of stone patients. The AUA guidelines contradict those of the ACP and, in my opinion, and his, properly so. This matters to you as patients. If your doctor has been told something is good and proper, by physicians promoted as experts by the ACP, he or she may act accordingly, and that may not be good for your care. Read what Dr. Goldfarb says, and likewise what I have said about this matter.


Get ready. We have covered stones, supersaturation, stone risk, potassium citrate, and more, but now we are coming to a central mystery – a pivotal issue in whether or not treatment will work or not. Calcium is the first name of most kidney stones, and the calcium in stones comes mainly from the urine. So the urine calcium is a big deal. Yet it is sodium chloride, humble table salt, that strongly controls how much calcium is in the urine. Genes play a role, protein, too, lots of factors. But salt intake is so modifiable, so amenable to change it has a massive role in treatment. Here is my best on the subject. I hope you like it.


This is the essential basis for modern kidney stone prevention. I review its limitations, and how much information it provides on the pattern of stone risk factors for a given patient. Also, I show how much variation within a day hides in the 24 hour averaging and what you should do about it, and point out why you need at least two 24 hour urines before treatment. If you have signed up for my emails, read the one for this article because it explains how it is put together and best read.


I have no illusions this will have mass appeal, but the topic is important and many patients may have an interest in how medicine and science work together in general and in this disease as a particular example. Unlike the rest of this site where I am redacting and elaborating well known themes, here I am forced into originality by the general poverty of writing on the subject. For those who like this kind of writing, the Site Logic Page is its natural home. For those who do not – no doubt a vast majority – pass by.


Obesity Is Epidemic World Wide Anyone can find ample evidence of US obesity. Here is a recent CDC map. In response, ‘bariatric’ surgeries designed to reduce body fat stores by limiting and re-routing nutrient absorption have risen to very high levels. The American Society for Metabolic and Bariatric Surgery estimates rates at 158,000 procedures in 2011 and 216,000 in 2016. Europe, and the rest of the world share the obesity problem. This is one of an almost endless number of graphs and maps I can put forward to document what is in fact a remarkable event in human history. Naturally, bariatric surgery rates have risen world wide, as they have in the US. The magnificent Tower of Babel Pieter Brueghel the Elder  (1526/1530–1569) hangs in the Kunsthistorisches Museum, … Continued

Citrate and the Ostwald Limit

This article will take you for a ride and offer you some surprises.

It is about how urine resists crystallization, a property summed up in the forbidding term ‘Upper Limit of Metastability.’

But don’t be scared off.

The ULM is a powerful concept that will help you understand the real issues in stone prevention.

And, at the end of the article, you will find that quite possibly it is not the mysterious and giant collection of urine proteins which protect us against crystals but perhaps our familiar citrate molecule in league with another small molecule, inorganic pyrophosphate which is a close relative of the bone sparing and common bisphosphonate drugs.


Potassium Citrate: The Contributions of Dr. Charles Pak

It seems to me important to highlight not only what we can do for stone prevention, but here and there to recognize those people who have given us what we have. Charles Pak’s work was instrumental in getting potassium citrate into the real world as a treatment. He helped to establish it worked, and helped industry make a practical pill form of it. As my tribute to him I have reviewed some his most important papers on the subject. Anyone who uses the drug should care.


This article is long and complex but I think patients will want to trouble themselves to read it. It tells the story of how our diet in the US, Europe, and urban Asia imposes an acid load which the kidneys must remove. That demand forces them to conserve citrate which is a natural defense against kidney stones. The pills neutralize the diet acid, and release the kidneys from their lifelong task of compensating for how we eat. That is why the urine citrate can rise. Removing acid is a major task that affects how kidney cells work. The humble potassium citrate pills have massive and probably beneficial effects on those cells. Of course, diet could the same as the pills, but how can one pursue a diet against the tendencies of the culture? Even with a will, most of us could not get it right – the balance of food, a proper nutrition. I could not advise we try.


Here is part two: citrate slows and can even stop stone crystals from growing. It does this by binding calcium, not the calcium in the urine but calcium atoms already part of a calcium stone crystal.

By binding to structural calcium atoms, citrate interferes with the orderly arrangement of atoms that is necessary for the crystal to exist, so one can think of inhibition and binding as two aspects of one power.

Like binding itself, this is not easy material to present or read. It is like climbing a tall hill for the view. If you will follow me up, I promise a reward.


The citrate molecule in urine is thought to protect against formation of calcium stones. This thought began as reasoning from chemistry, and culminated in clinical trials which substantiate the idea. As a result manufacturers produce citrate products for medicinal use, and doctors prescribe the medicine. All this is a wonderful success story, a kind of perfection of the paradigm of translational science: From science to a treatment for patients that reduces illness from kidney stone disease. But what, exactly, is the science? Can scientists not enjoy the story of such a success, physicians derive from it a deeper understanding of the drug they so regularly dispense and patients the comfort that a perfected knowledge support the rightness of their prescribed treatment? Citrate The Molecule As … Continued


Potassium citrate, thiazide diuretic agents, and allopurinol are the three medications that have a proven ability to reduce kidney stone formation.

Because fluids are so valuable and safe, we have emphasized their use as a basic treatment for all forms of stone disease. Here, I present the evidence that potassium citrate adds protection. The evidence is in the form of 5 trials that appear well done.

Some of the background for this article was already prevented in our discussion of the costs of this drug. Likewise, that discussion presented alternative sources of alkali that should more or less mimic the protective effects of the drug despite lack of direct trial data. I say this because the drug is a simple alkaline salt. 

The article is written for anyone. Physicians will fill in more blanks than patients, but patients can easily analyse the numbers.


I have alluded to objectives in my discussion of applied, basic, and empirical science, which was a good place for their first mention but too narrow for a proper exposition. They are in the first case an expression of need, in the second case of desire, and in the third arise from perhaps an altogether different source. Here I am concerned with objectives of applied medical science. The delightful painting by Frank O’Dea can be purchased through the link. It is indeed named “Reaching our objectives”. CLASSES OF NEEDS What can be the perceived needs of medicine but treatments, prevention, tests – to aid diagnosis or prognosis, methods, techniques and devices? EXAMPLES OF EACH CLASS Consider a patient with calcium oxalate stones … Continued


This post concerns guidelines just released by the American College of Physicians (ACP) concerning prevention of calcium kidney stones. In the article two specific guidelines are proposed. The first, on fluid management, is covered in another post. Here I discuss their views concerning uses of medication. The discussion here is in advance of what is already on the site. Whereas I and others have put up more than a few articles about fluids, the issue of medications has not arisen. This is because medications have always been used to alter excretion rates of three atoms or molecules in urine thought to alter risk of calcium kidney stones: calcium, citrate, and uric acid. I have not as yet set the foundation for discussion of … Continued


The American College of Physicians has published its Clinical Guidelines on dietary and pharmacological management of kidney stones in adults. My purposes are to place the results of their deliberations in clinical context and also draw some conclusions about research we might want to perform. Though only two in number, their recommendations cover virtually our entire field of practice. For this reason I thought it best to consider each of the two separately, in different posts. As a simplification, I accept the statistical analysis as correct. Partly I suspect it is correct. Partly, I am not engaged with the methods of the analysis so much as I am with how we view their results and their conclusions. The ACP Guidelines can be influential among primary care physicians. As people involved with … Continued


WHAT IS THE QUESTION? I understand that some physicians are skilled basic scientists, and that many physicians enjoy reading about basic science. But how does a knowledge of basic science benefit the patients of physicians who have such knowledge? There are two parts to this question. How can being a basic scientist benefit a physician in the practice of medicine, and how can a knowledge of the results of basic science benefit a physician in the practice of medicine. Of these two, I mean to consider only the second: How does a knowledge of basic science results benefit the practice of medicine. Of course, here, I mean practice of medicine concerned with kidney stones – the disease within the province of this site … Continued


Three Sciences of Medicine Certainly we all agree that modern medicine takes its power from science. One kind of science concerns how we can do things. Let me call it ‘applied science’ for want of a name. The other kind concerns how nature does things. This is often called ‘basic science’ or ‘natural science’. Drug development and drug trials are obvious examples of the first. Mechanisms of disease are examples of the second. These statements are so obvious I hesitate to make them, yet in such phrases as ‘evidence based medicine’, ‘basic vs. applied science’, ‘personalized medicine’, and ‘translational research’ the distinction, itself perfectly clear, can blur. If basic science seeks to learn how nature does things, empirical science seeks to … Continued


How does anyone really know the amount of fluids you need for stone prevention? Dr. Elaine Worcester and I have put together much of what is known about the topic and offer some reasonable guidelines. Our caveat: These are guidelines, but have your physician do the final decision. Not everyone can drink large amounts of fluids, and not every patient needs the maximum amount, either.


I never have been a remarkable shopper, so those who know me well might wonder at a post about prices. Even so, patients have complained and wanted alternatives to potassium citrate pills which have become too costly for them. I did a bit of web shopping for retail prices, and although they vary, even the lowest seem too high for most budgets. A very brief look at insurance plans under Medicare: Some plans just pay the whole bill; some charge $10.00 for 100 pills; some charge a percentage of retail; some do not pay. So I have put together alternatives which taken in aggregate permit everyone to piece together a replacement for all or at least some fraction of these pills whose price has become just too high.


The complex but interesting featured graphic introduces aspects of the innate immune system which is present and active in the kidney and may have a role in stone genesis. Although innate immunity in kidney is a well established area of research, the specific links to plaque and stone formation have not been explored thus far. So, my post is meant to interest people in the possibility and perhaps give rise to some new scientific research. Toll Like Receptors (TLRs) The innate immune system is an ancient system of defense against environmental threats that is found in all classes of plant and animal life. Innate immunity provides immediate, non-specific defense against infection and products of cell damage or stress. Toll-like receptors (TLRs), … Continued


Something In their Papillae Video: The Story With Less Detail  The papilla is where urine leaves the kidney. It is where plaque forms, and plugs. Most calcium stones form there. Though just a few millimeters long, those few millimeters extract water and supersaturate the urine  – the supersaturations create stones.  Take a look at how the kidney is put together, if you do not remember. Stone Former Papillae Absorb More CT Radiation than Normal On CT, the papillae of stone formers are darker gray than normal – more dense. You cannot see it, too subtle. But the routine tools on every CT reader let you measure density – how much radiation is blocked. The density is in Hounsfield units, HU, higher … Continued


Supersaturation Supersaturation names the force that makes crystals. Because it does, we measure supersaturation to understand why a patient makes stones, and we reduce risk of more stones by lowering supersaturation. Fortunately, universal and quantitative laws govern how atoms and molecules form crystals so we can calculate supersaturation and predict the risk of crystals using equations that apply everywhere, even in the kidneys and urine. Supersaturate a solution yourself, and see how it works. Supersaturate your own sugar solution Saturate Your Sugar Solution Find a heat resistant glass container, fill it with water, and stir in table sugar until no more will dissolve. You will know when no more will dissolve because extra sugar remains at the bottom even if you shake … Continued


A NEW AND USEFUL REVIEW THE FUNDAMENTAL MEASUREMENT OF STONE PROPENSITY The three Moirai, or the triumph of death, Flemish tapestry ca 1520, Victoria and Albert Museum, London, depicts Clotho, who spins the thread of life, Lachesis, who measures out the length of the thread, and Atropos, the inexorable, who cuts the thread. In book 11 of the Odyssey, Odysseus travels to the underworld where, among other matters, he learns from Tiresias his own ‘fate’; that he will return to his home and his own wife; that he will travel again to a place so far from the sea his oar will go unrecognized; and that he will die in peace, by the sea and among his own people. But he must make an offering in … Continued

Chapter 11: Ileostomy and Kidney Stones

The large picture shows a papillum of a patient with ileostomy as seen at surgery for stone removal. The large white patch between the arrows is plaque, the stuff calcium oxalate stones can anchor to and grow on. The yellow material between arrowheads is terminal ducts of Bellini (BD) plugged with crystals. Both are abundant in patients with ileostomy and part of how they form stones. This article relies on only three research publications, and in all modesty I must admit they arose from our research group. But in defense, one is remarkably comprehensive and one the only one with detailed study of kidney tissue obtained during stone surgery. Also in defense, their reference lists are good enough to give … Continued


Hard unwanted objects made in the kidneys, stones can cause pain, bleeding, and urinary tract obstruction. Because stone surgery often infects the urinary system, and bacteria easily infect stones retained in the kidneys, infection follow stones like a shadow. Stones surprise patients by their smallness, for all the trouble they cause, or by their largeness to think they passed through the urinary tract. But small or large, many or few, stones provoke little love. Most who form them desire no more. Yet, left to themselves, stones recur. Over half of first time stone formers form another stone within 5 – 10 years. Once recurrent, stones form – on average – every 2 – 4  years. So stone patients must pursue prevention and not imagine their … Continued


A particular manner Here and there physician friends have asked me about how I practice. But however much I have written about kidney stones, nowhere before have I told about how I practice because I feared my style might seem too odd. But it is not if you consider how narrowly I have chosen to focus. My clinical life is based on several facts. One is that doctors send me their patients and expect that I will prevent recurrent stones. That is all they want from me. This means that I can depend on other physicians to do everything else, focus on the pathogenesis of kidney stones in a particular patient and fashion for that patient a program of prevention which will … Continued


Kidney stone types Crystals make stones and their names signify the kidney stone types. Here are the names of the crystals that make the stones: CAOX, Calcium Oxalate; CAP, Calcium phosphate; UA, Uric Acid; Cystine; Struvite. The wedges on my pie chart show the relative abundances of stone types in our large population of stone forming patients. Calcium oxalate stones predominate by a wide margin in our clinic and in all others I know of. The names, matter because the whole science of stone prevention focuses upon stone crystals. Each kidney stone crystal creates its own unique illness and requires specific treatment. That is why we name stones by the names of their crystals and why when stones are analysed the results are … Continued


How bad is kidney stone analysis? I have pointed out the crucial importance of kidney stone analysis. Likewise, if possible, I analyse every stone because crystal type can change. But does this not raise the obvious question: How good are stone analysis labs? At first one might say why ask? We use labs all the time and trust them. As things turn out, stone analysis varies more in quality than serum electrolytes, or blood hemoglobin. Moreover, some stone crystals pose greater problems than others. There is a gold standard X Ray Diffraction Basiri et al recently reviewed all available papers concerning analysis of kidney stone crystals. Like prior investigators, some of whom they reference, X-ray diffraction does indeed reveal stone crystal structures … Continued


When I wrote the original article in 2014 limitations of proteomics seemed the main obstacle. This new work by Dr Frank Witzmann shows us the other side of the problem. A master of the modern proteomic techniques, with them Frank shows that the number of unique proteins in just two human calcium oxalate kidney stones is over 1,000. If inadequacy of technique stymied us two years ago, inadequacy of intellect – at least of mine – stymies at least me, now. What to make of so many proteins! What are they doing there? Which ones matter in stone genesis? We have the methods, we have stones to work on, but what shall we ask? As always, the magic is in the vision.


There is no doubt about what I say to patients: ” Analyse every kidney stone. Bring in any stones you have tucked in a dresser drawer and get them analysed. Bring me all the analyses that have been performed on your kidney stones.” But what do I say to me, and what do I do as time goes on and more stones form or are passed? Do I analyse every kidney stone? Do you? The problem of keeping track Whenever I get a new patient, the stone analyses are at the top of my mind. How can I do anything rational about prevention if I don’t know what the stone crystals are? If there are no analyses at the first … Continued

Chapter 12: Distal Renal Tubular Acidosis

I do not know why anyone would diagnose distal RTA (dRTA) very often. As I will show you it has colorful and unusual characteristics as unmistakable as rare, so diagnosis is not difficult. But many more people think they have than have it. In my 50 years of kidney stone prevention I have perhaps a few dozen examples or so, out of many thousands of stone formers. This is another of those long, elaborate articles only the most devoted read. Even so, elaborate as it is, this article tells only part of the story. It simplifies or simply ignores the mechanism for low potassium in dRTA, and left for another time its genetic causes, and also the bone and mineral … Continued