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Medullary Sponge Kidney – A Case

So many patients have, or are said to have MSK I thought this person would be of great interest. You cannot identify him as all personal information is blurred but his disease is clearly marked by intraoperative images and tissue biopsy as certain, and my work with him as his physician also marked – by failure of recognition right up to the diagnostic surgery. The message is the same as one we have offered before – MSK is hard to recognize. It is a name that is easily attached to patients with other diseases. As compared to our larger article about MSK in general, this one is granular and exact. It depicts MSK as it was in one person, and therefore offers a portrait from life.

Take Charge of Your Kidney Stone Prevention

Patients have loved Jill Harris’s articles for their sensible approach and gracious style. Here she takes on the pragmatic side of the two big issues shown just below: The merging of the kidney stone prevention diet with the US recommended diet – what I now call The kidney stone diet – and the problems of how to eat such a diet in real life and for the long term. If you put the two issues – what is the diet and how do I eat it? – together with the whole complex of testing and follow up patients face a formidable challenge to integrate what they need to do with what they need from their physicians. In this article Jill clarifies the roles of patient and physician in her lapidary but charming way and even adds a few cartoons to lighten things up. It is must reading for patients, and easy reading, too.

Take Charge of your Stone Prevention  What do you do vs. what must your physician do to achieve kidney stone prevention
Be a successful patient Get the most from your physician visit
Five steps to prevention What patients need to do
How to read lab reports: calcium Identify and track problems: calcium stones
How to read lab reports: uric acid Identify and track problems: uric acid stones
My Lab Report Two nifty lists to pin on the fridge door
Putting it all together How stone prevention works
How To Eat the Kidney Stone Diet How the kidney stone diet and Healthy American diets differ
The Kidney Stone Diet The diet for stone prevention – sums up the detailed articles
Low Oxalate Diet Advice and lists
High Calcium Low Sodium Diet Advice and lists
Low Sodium Diet Advice and meal planning
High Fluid Intake Beverages and advice
Diet Protein Intake Advice and effects on bone and stones
Prevention of Idiopathic Calcium Stones The most important article on the site
Cases Examples of actual – but disguised – patients


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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


I thought it was time to sum things up, to offer an utterly practical guide to stone prevention. So here it is. You have kidney stones, even one, what next? There are things you need to have your physicians do for you. There are things you need to do for yourself. Then, there are things that may not need physicians but other kinds of support. To unclutter the text I listed the key links at the end of the article.  WHAT YOUR PHYSICIANS NEED TO DO Stones can come from systemic diseases, and only a physician can determine if that is the case for you. A not uncommon example is primary hyperparathyroidism that is curable but with surgery. There is a … 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.’ Of course, we are speaking of the diet for treatment of idiopathic calcium stones. Stones from systemic diseases, like bowel disease, primary … Continued


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

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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.

crystal for article

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.


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.


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.

low salt cottge cheese

Many patients assume that they are forming calcium stones and should therefore limit their calcium intake. That assumption could not be more wrong. Low calcium diet won’t stop your stones and may even increase your risk. Lets not forget that our bones are in desperate need of calcium to avoid osteopenia and osteoporosis. But, many of the best foods for calcium are also high in sodium, and sodium raises urine calcium loss and stone risk. Now what? How Much Calcium do We Need? The National Institutes of Health tells us age matters. Nineteen to fifty year old male or female need 1,000 mg of calcium a day. Fifty one to seventy year olds need 1,000 mg for males and 1,200 … Continued

kidneystonerss site

This is a very first for me: Recommending a kidney stone site to those who visit here. Although the internet is vast and even a casual search shows a lot of kidney stone sites, this one stand out because it has all the traits I respect. It is run by a fine and thoughtful urological surgeon with special skills in kidney stone surgery. It has very high academic, intellectual, and scientific standards. It is large and therefore has a lot of material in it whereas many otherwise good sites are small and limited. It has a distinctive tilt toward patients, and a tradition of having patients write articles on it. For people who like this site, will feel famiiar yet different enough in its emphasis that to me the sites are highly complementary. Take a look and let me know what you think.

download web app logo

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.

blue door andrew wyeth

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.

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Dr. Mike Borofsky authored a favorite article on this site – Pain from Kidney Stones. Now, he has authored our first article on stone urology, meaning the urological surgeries used for treatment of stones in the kidneys and urinary tract. Ureteroscopy is fast becoming the preferred approach, outstripping shock wave lithotripsy and percutaneous lithotripsy. This is because the instruments for ureteroscopy offer superior optics and are flexible and small enough to get from the urethra up into the kidneys and into all of the crevices of the kidneys where stones form and lodge. Armed with tiny but powerful laser fibers, the new ureteroscopes permit surgeons to fracture stones in the kidneys and turn them into mostly harmless dust that passes silently for days or weeks thereafter, or into small fragments they take out during the procedure leaving not a speck behind. It is a brilliant time to be a young urologist and use these marvelous instruments to do what would otherwise require a far more complex and risky procedure (percutaneous nephrolithotomy) or depend upon an indirect and often incompletely effective one (shock wave lithotripsy).

uric acid crystals nejm199403173301106_f1

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.

lab report image shutterstock_119953213

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 three thiazides

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. 


As part of a series, Jill offers this long and critical article on restricting diet oxalate. The problem is very complicated because oxalate is in a lot of plant foods and these are foods we need and often like. Using the Harvard oxalate list with cross referencing with another list from an excellent academic institution, Jill finds her way between the problems of too much oxalate and too little to eat. She offers a whole day meal plan outline people can fill in with their own preferences. Some key scientific papers are reviewed at the end to show the basis for her advice.

low salt diet

Jill Harris offers another of her amazingly useful and popular articles, this one on the how of low sodium diets. As she has done for fluids, Jill takes you into her own kitchen and dining room and shows you how to limit salt intake and yet fully enjoy your meals. She has had years of experience coaching patients about exactly this kind of crucial life management, and it shows. Her articles are the most popular on this site, and this one is destined to join her others in helping thousands of people actually do what their physicians ask them to do: Eat less salt to stop making stones.

bone biopsy in IH

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.

fuller albright

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.

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Many people have multiple calcification in their kidneys and urinary tracts which show up on CT scans and are labelled ‘nephrocalcinosis’. When they look like multiple small calcifications massed together radiologists often label the disorder as MSK. Old fashioned x-rays with contrast agents were actually more discriminating for the diagnosis but have passed into disuse. Contrast CT can also help make the diagnosis but is rarely used to diagnose stones. Modern high resolution endoscopy has, fortunately, taken over as the main new way to manage stones and with such instruments surgeons can confidently diagnose MSK. Because new, the change in the way we diagnose MSK will inevitably change what people are told is the cause of their stones. MSK has special features which complicate treatment. A large majority of people presently labelled as having MSK probably do not have it but rather have one or another more common stone forming disease. The message is simple: We need to separate out who has what and provide exacting and reliable treatment using the most modern techniques.

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Dr Michael Borofsky is a young and brilliant surgeon specially trained in kidney stone management who offers us the article any patient or family member or friend will want to devour. Stone pain is awful and arises from complex abnormalities that are important to know about. He makes clear how much inflammation occurs, why a lessening of pain might not signal betterment of obstruction but only a fall in blood flow to the kidney. Most importantly he writes about the possibility that stones which do not obstruct might still cause enough pain to disable people, interfere with life, and lead to drug dependence. This controversial area of kidney stone surgery requires new studies, but before they are done patients and physicians need to know about the possibility that chronic pain in a stone former may be coming from an innocent appearing stone we have up till now dismissed.

urine collection bottle

So many times I have been misled and my patients also because of misunderstandings about what 24 hour urine collections can tell us. They are single frames out of a movie that runs lifelong so it is imperative people collect as they were when they made stones or as they are pursuing their stone prevention treatments. The concept is easy and easy to ignore, put aside, forget about. Jill’s offering is not only useful for the first time collector, but every time – as a reminder.

Raphael School of Athens

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.


A very useful introduction by Dr Anna Zisman. In general the articles on this site are a bit more detailed and referenced than this one, but the disease is very complex and we thought a fairly simple and brief introduction would be ideal for patients and their families.


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.



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.

picture of citrate effects on COM crystals

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.

ca citrate crystal12584

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.

ICJ-CJI_hearing_1 judges

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

ICJ-CJI_hearing_1 judges

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


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.


Well and good to say, ‘Drink 3 liters of water a day to prevent kidney stones’, and go on to something else. It is another to accomplish that feat. Don’t some drinks raise stone risk – like coffee and tea? What about Coke, diet drinks, beer and wine? Is anyone supposed to make do on all water? Here is a post by Jill Harris that offers answers and even daily menus of beverages. As things turn out, there are a lot of choices, a lot of ways to get in all that fluid, every day. 

potassium citrate pill

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 Web abounds in lore about kidney stones, perhaps because stones are common, and perhaps because they are painful and people want remedies. This particular remedy caught the eye of Dr. Anna Zisman because one of her patients read about it, tried it, and seemed to get worse instead of better. She did some research on the matter and decided it was worth while to let patients know that the treatment is not ideal and possibly can do a modest amount of harm. Her charming and useful message is typical of her critical and thoughtful analysis of medicine, and especially this tiny but active area of stone prevention.


One might think nothing is easier than drinking water; my experience is that nothing is a lot harder, as least for a large fraction of patients. The new post by Jill Harris is all about how. Jill spent 12 years at Litholink corporation, now a subsidiary of LabCorp, supervising their team of telephone patient care representatives. Her team, and she herself, dealt with thousands of patients, and how to drink enough water was always a large issue. As practice will do, she has gradually built up her bag of tricks for patients, and shares some of them here, with you. Now in her own practice, Jill continues to help people prevent stones by showing them how to actually accomplish what their doctors urge them to do.


Supersaturation Because crystals are at the heart of all kidney stones, when we talk about preventing stones we mean preventing crystals from forming and from growing. Fortunately, universal and quantitative laws govern how atoms and molecules form crystals so we can predict the risk of crystals using equations that apply everywhere, even in the kidneys and urine. Supersaturate your own sugar solution One way to understand these laws is to make crystals on your own. Find a heat resistant glass container, fill it with water, and stir in table sugar until no more will dissolve and there is extra sugar at the bottom. The water is ‘saturated’ with sugar, meaning it holds all it can. It is ‘full’ of sugar. … 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


A few general words about kidney stones I suppose anyone who produces kidney stones knows they are hard and unwanted objects made in the kidney that cause pain, bleeding, and obstruction of the urinary tract, and lead to urinary infections and surgery. Most patients come to realize that stones recur, because over half of those who have formed only one stone will form another within 5 – 10 years. Many patients have seen the stones they form, black, or orange, or yellow, or gray, smooth or spiky, surprisingly small for all the trouble they cause, or surprisingly large to think it really passed through the urinary tract. All patients who have formed stones, at least all the ones I have ever met, want … 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


The crystals of the common kidney stones I suppose I could have made my pie chart smaller but I wanted it to shine out like some odd colored moon because the names of the stones are so important and so much of what we do depends upon knowing them. They names of kidney stones are the names of the crystals which make up the hard part of the stones: CAOX, Calcium Oxalate; CAP, Calcium phosphate; UA, Uric Acid; Cystine; Struvite. The pie wedges show their relative abundances to each other in our large population of stone forming patients. Calcium oxalate stones are the most common by a wide margin, and that has been true in every accounting of stone types I … Continued

From Journal of Urology 184:1543-1549, 2010

Two related posts, for patients and for physicians, emphasize the fundamental importance of the kidney stone crystal composition in management of kidney stones and by direct extension the importance to patients and their physicians of sending stones for analysis. Here, in a scientific forum, one needs to raise the obvious and complementary issue of quality: can patients and their physicians rely on the results of stone analyses? There is a gold standard Basiri et al recently reviewed all available papers concerning analysis of kidney stone crystals. Like many others, some of whom they reference, X-ray diffraction does indeed reveal the crystal structures and if applied to several regions of a stone is perhaps the ideal method on which to base research … Continued

From Okamura et al; see reference link in post.

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: “Bring me all the analyses that have been performed on your kidney stones. Bring in any stones you have tucked in a dresser drawer and we will get them analysed.” 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 all of them? 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 visit, like you … Continued