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Patients can read and hopefully enjoy anything on the site, but these articles were written to them and for them. My purpose is to enable every patient to make the most of their medical visits and do for themselves what they can do to help prevent stones.

Several writers for the site have been very popular with patients and so I thought I should make clear who they are.

A number of very popular articles were written by Jill Harris, and perhaps you might want to know more about her. She is in private practice as an advisor to stone patients on how to manage diet and fluid recommendations given to patients by their physicians.

Likewise, Dr. Mike Borofsky has given us some vital articles on surgery and stone pain. He is a urological surgeon now on the faculty of University of Minnesota.

Be a successful kidney stone patient Get the most from your physician visit
The five steps to stone prevention How prevention works, what patients need to do
How to read 24 hr urine reports: calcium Spot your problems, track your progress: calcium stones
How to read 24 hr urine reports: uric acid Spot your problems, track your progress: uric acid stones
My Lab Report – Five Questions Two nifty lists to pin on the fridge door
Putting it all together Stone prevention from 50,000 feet
Low Oxalate Diet How to eat a low oxalate diet
Prevention of Idiopathic Calcium Stones The most important article on the site – How to conduct rational stone prevention



Here are some of you. These two people are recent patients of mine with idiopathic calcium stones. They are here because in their findings and the problems of prevention you can see as if in a play all of the ideas and facts on the site brought into action. Some of it is the sheer mass of work needed to get records and scans and stone reports all together to make visits effective. A lot of is the complexity of putting very clear principles of supersaturation reduction into practice. I have put these cases on their own page, with its own tab, to signify that they will be a major part of the site, which is large enough now to support their discussion. The viewpoint of the cases is a bit from that of a physician, but there is no jargon and if you are a reader of this site there is nothing you have not or could not read.

Prevention of Idiopathic Calcium Stones

The whole site was built to lead up to this most important article. It has in it all of the trials, and all of the ways that idiopathic calcium stones can be prevented. It discusses all treatments and shows what there is of trials to test their ability to prevent stones. For experts or highly motivated people in general I have put in place spreadsheets that summarize the critical trial data, and PDF images of the original papers. From all of the analyses I present my own approach, which is not remarkably different – I suspect – from what many physicians do and is based solidly on the scientific evidence we have, both from trials and from more basic research. I have left in red the videos because they were meant as stepping stones up to this final article on idiopathic calcium stones. Likewise the two articles that precede the videos, on the phenotypes, are invaluable background for understanding treatment. Although this article is difficult, patients can read it as jargon is left out. I will be putting up a video version with greater availability.

Video: Supersaturation

My site has a lot of articles on supersaturation because supersaturation is the single best statement of stone crystal risk both in theory and practically, too. The video format helps to pull together all of the information in the articles, and do so in a way that seems more compelling and integrative. I have divided the topic into three short videos meant to be seen in order but certainly not at one sitting. The first concerns what supersaturation really is. The second is about superated urine as a loaded gun, and how kidneys produce it. The third is about how supersaturation is measured and actually used in stone prevention. It is the most important of the three and longest. The article includes some commentary on the videos and links to all of the other supersaturation articles on the site.

Video: How Stones Form

I made this video specially for patients. It is the first of what I plan for as a series of additions. The purpose of the new medium is clarity and range. This covers about 4 – 5 articles in what I think is a clearer but less rigorous format. The topic is how crystals form, how they are made, how they form and grow specifically in the kidney, what happens in the kidneys because of them, and how the small deposits become kidney stones. As an apology up front: This is truely beta quality as I am learning how to do it. Medical videos at a high level of rigor and complexity are not so common for general public attention, so I am perhaps a bit vanguard. I am also hopelessly amateur in the medium – though I will learn. So, please ignore the lack of polish for the moment but help me know if this is getting things across.

Idiopathic Calcium  Phosphate Stone Formers

This is the other great division of stone disease. Instead of calcium oxalate as a main stone constituent, these patients produce stones with a predominance (above 50%) of calcium phosphate. Moreover, there are two different forms of calcium phosphate – hydroxyapatite (HA) and brushite (BR), and those with any BR in their stones are different enough from the others to warrant their own grouping (BRSF) vs. those whose stones are only HA (HASF). Although less common than calcium oxalate stone formers, the HASF and BRSF may have more troubles. It is not that they have more stones, but their stones form not only as overgrowths on plaque but as plugs that form inside the kidney tubules, injuring them. Plugging is not unique to calcium phosphate stone formers, quite the opposite, it is the rule in almost all stone diseases except idiopathic calcium oxalate stones. HASF and BRSF are sometimes thought to have one of the systemic diseases, such as renal tubular acidosis or primary hyperparathyroidism. Likewise their many plugs along with retained stones can produce nephrocalcinosis which can be mislabeled as medullary sponge kidney. Fortunately calcium phosphate stone formers can be treated in much the same way as calcium oxalate stone formers, and prevention of recurrence may be more or less as effective. So efforts at prevention are of great importance. Please consider watching this video I made as an introduction; the article is long and complex, and perhaps it will make things easier to understand. 

Idiopathic Calcium Oxalate Stone Formers

Although long and complex this is an article for patients with stones to read and pay attention to. The idiopathic calcium oxalate stone forming phenotype is very common, and therefore most of you who read this probably fall into that category. If you do, read about how your stones form, and what abnormalities are typically found in your kidneys. This will help you when your surgeon, equipped with modern flexible ureteroscopy as a stone removal modality, tells you about such things as plaque and plugging, and stones growing on your kidney surfaces. If you do not fit into this category, wait a while because I mean to write articles about all of the kinds of stone formers, and your turn will come. Here is a brief movie that introduces the article and adds a few details.

A Great Site for Patients

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.

Michelle and Pat – A Success Story

Here is an article written directly for patients, or, better said, for those who love and care for patients with stones. It was written by the wife of a man with calcium stones due to idiopathic hypercalciuria – a very common condition in stone formers. Thiazide diuretics are a proven treatment that will lower urine calcium and in fact reduce production of new stones. But her husband operates heavy equipment and is exposed to high heat in summer so the idea of that kind of a medication raised issues of dehydration and possible risk. The better choice would be low sodium diet, which can lower urine calcium just as well as thiazide but requires a lot more from the family. That ‘lot more’ often means failure to achieve the needed fall in diet sodium, and eventually more stones. In this case, diet succeeded, and that is because his wife found a way to make it happen, and he was willing to limit himself to what she could provide. Michelle, who is a professional writer, was kind enough to write about how she did it, and Pat was willing for me to use his real name and mention his medical details. I have made a brief movie that is a bit more specific about the urine calcium, how sodium affects urine calcium, and where on the calcium – sodium axis Pat began and – with help – ended up. I think this is a remarkable story about what can be done with simple, safe, and inexpensive – if laborious – measures to prevent stones. I want to publically thank Michelle and Pat for letting us all share.

Control of Urine Oxalate Excretion

I am nor sure how to speak to patients about this article. Urine oxalate is a major issue in stone prevention, and we have already done as much as we can to provide the most up to date and accurate food oxalate lists available. How the intestines and kidneys manage oxalate is now becoming clear from a decade of inspired research. Much of the progress concerns the molecular transporters that permit oxalate to enter and leave the body, and my brilliant colleague Dr Hatim Hassan has written about them in this article. Should patients be bothered to read about all this? Practically, no; there are no current clinical implications. But the future may lie here, in regulation of these transporters, and some may want to know. I have made a brief movie to introduce the article. Perhaps it may help you decide. 

The Proteins in Kidney Stones

I first wrote this article in 2014 and called it ‘The Majestic Void‘ which title remains. What has happened recently is that the void has become more majestic but remains a void in that we look into it or on it in puzzlement. The new results from the most modern proteomic techniques show us over 1,000 proteins in only two calcium oxalate stones. That many. Surely most are not essential to making a stone, but some are. Crystals alone make no stones, you need something to bind them together, and that something is some mix of these proteins. If we were ignorant before of what is there, we are ignorant now of what what is there is doing there. It matters. If we knew which molecules were important, we would have clues, clues to who is at risk of stones, perhaps, clues to how one might fashion some inhibitor molecule. But here we are, with knowledge sans understanding, one step better than we were, but nowhere where it counts.

Web Apps and Smart Bottles

I have never before copied from the Home Page onto the three specific pages, but here there is no choice. This article is a simple plea for everyone to share their experiences so everyone can benefit. There is nothing more to say and nothing more said. Please share.

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.

My Lab Report – Five Questions

A kind of ‘Little Engine that Could’ this nifty questionnaire just wrote itself one evening. As I said on the front page a colleague was pushing me to come up with something simpler than the two longer articles on how to read your own lab reports. If you use it and refer to the other two article on reading lab reports you should be able to put together your diet and fluid plan reasonably well yourself. It has two sections, the first is for the initial labs in your life, the second is the add on when you have follow up labs – you do the five questions in Part One and then the two questions in Part Two. The final actions are briefly stated but I have put in links from each action to the article that tell you how to do it – for example drink more. I really would appreciate your feedback – good or bad, but please not too nasty. I think this format has a lot of promise but could use fine tuning.

Putting it All Together

I view this as my uber article, the one that reaches into the others and draws them together. The others are how to be a successful kidney stone patient, five steps to stone prevention, and how to read 24 hour urine laboratory reports for calcium and uric acid stones. Five steps is an overview, how to be successful has the lists and time management suggestions to optimize physician visits and pursue long term prevention, and the two articles on reading laboratory reports are about technique. This one seeks to integrate the four into a template and sequence. Now that I have them in place there are regrets. Perhaps I should have made some differently or written them in knowledge of each other. But I did not really know what each would look like until I had them done – that is the truth about writers, planning goes only so far. There is enough, and well enough put together, that any patient with will and effort can make the best use of their testing and physicians, and of themselves as well in the service of prevention. What I need most is for patients to tell me what might have worked better, for I can re-shape things over time in this so forgiving medium of electrons, if only I know what shape the final shape should be.


To me any stone is a failure of our profession, for prevention rules over all treatment. Even so, we fail often enough and must contrive a way to better things and that way, here, is removal of stones that have formed despite us and cannot be left behind. Technology advances have carried ureteroscopy to the top of the mountain, so it is preferred over shock wave and percutaneous lithotripsy in most cases. Slim and capable the modern scope armed with its tiny laser fiber and driven by a skilled surgeon reminds me of a nuclear submarine, beautiful and deadly – in this case to an unwanted stone. Mike Borofsky exemplifies those techy and brilliant graduates of outstanding fellowship programs presently training what I might call ‘next gen urologists’. Here is his bright and clear story about the new way things are being done.

How To Read Your 24 Hour Urine Report – Uric Acid Stones

This is the second of the two articles. If their titles seem to link them that is because they are two halves of one project. For uric acid one needs to read lab values for urine pH, ammonia, and sulfate along with the numbers already presented for calcium stones. This means that whatever your stone type you should read the first article. If you have uric acid in stones, or have uric acid stones, read this one, for sure. If you do not, it is interesting and worthwhile but not necessary.

At this point I am ready to reveal a long intended purpose and underlying plan perhaps already obvious, perhaps not.

These two articles, the one on how to make the best use of your physician visits and treatment regimes, and the ones on the main treatments – fluids, sodium, oxalate, thiazide and potassium citrate, all were created to actuate the One ArticleFive Steps to Stone Prevention. That article is the primary directive of the site, the apex of the pyramid, which, all of its secondary articles written, can assume, now, its intended primacy. The whole site will reorient around the one theme: Prevention and its realistic achievement, all else becoming what it is, a means, merely, of such achievement.

How To Read Your 24 Hour Urine Report – Calcium Stones

You can read your own 24 hour urine tests well enough that you can actively participate in your own stone prevention. The barriers are mainly the sheer number of numbers, confusing units, and a strategy. Here is what to look for if you form calcium stones. The main lab results are urine volume, calcium, oxalate, sodium, citrate and pH, and the supersaturations for calcium oxalate and calcium phosphate. Urine creatinine lets you decide if you collected your urines consistently and well. The diet and fluid and lifestyle changes you make should change urine chemistry results, and you can look for yourself and see how well you are doing. This site has a lot of the background information you need to understand how urine abnormalities come about and how they promote crystallization and stones. It is time now to read for yourself what abnormalities lurk in your own urine chemistries so that your enthusiasm and desire for change might increase and, as a reader of the map and compass you can help set the course.

Thiazide Diuretics for Stone Prevention

Like potassium citrate, thiazide type diuretics are major drugs that can all by themselves lower stone recurrence. They are widely used. This article is for patients who want to know the evidence that they work, how they work, and what else they might do beside prevent stones. I cannot say often enough that both medications are best used on top of what can be done with fluids, diet, and lifestyle changes to lower supersaturations. When these measures are not enough the drugs can make all the difference. But, often they are enough and drugs are not needed. In this decision, to use them or not, is a lot of clinical acumen from physicians and a lot of personal insight from patients concerning what they realistically accomplish for themselves. Shun the simple prescription for a pill, as it may be avoided by what I just mentioned. Likewise be wary if stones continue despite fluids and diet and other changes – thiazide might be crucial. Ask for it if you need to. But be sure you have done all you can beforehand.

The 5 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

How To Eat a Low Oxalate Diet

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.

How To Eat a Low Sodium 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.

Control Your Salt for Fewer Stones and Stronger Bones

Here is an article for you. It is not easy – I guess I am not so good at that – but practical and about treatment. The trials are certainly not done, but there is enough evidence for this: Reduce your diet sodium below 100 mmol (2300 mg) daily, raise your diet calcium up to the US recommended level of 1,000 to 1,200 mg daily, and keep your protein intake moderate. These changes are very likely to reduce new stones and protect bones against mineral loss. When you read the article you will see that I am in advance of formal trials. There is only one good salt trial for stones, and one good salt and calcium trial for bones. The former was done in Italy – different cuisine – and involved only men with idiopathic hypercalciuria and calcium oxalate stones. The latter was done in the UK and involved bones of menopausal subjects who were not stone formers. Do we need trials for men and women with stones? Yes. Will we have them soon? No. Is there any danger or risk from lower diet sodium and higher diet calcium? No. I think it is time to just do it.

How to be a Successful Kidney Stone Patient

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 (IH)

NB. This article has been edited for clarity. Summaries are added in bold italic.

For patients with calcium stones, IH is perhaps ‘the’ crucial issue. It is not by any means the only important cause of stones, but it is common as a cause of stones and bone disease, complex, familial, a main stone cause in children, and at the center of the most common treatments that must at the same time reduce stone recurrence and protect against bone mineral loss and subsequent fractures. In pursuit of stone prevention with diet changes and adjustment to medications, patients are best off with a solid knowledge of how IH works. All the treatments work through reasonably well defined pathways, so if you know them you can help manage diet changes in an informed way, and understand how diet interacts with medications. Most important is how IH can affect both bone and stone disease and how when used properly treatments can prevent problems in both areas at the same time. Consider this article more a resource than a single read. It is very long but written with a minimum of jargon so patients can use it for their information. So far as I can achieve it, the article is scientifically correct in relationship to the state of science in the area, and I plan to keep it current. 

Hypercalciuria – An Introduction

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.

Two Related Articles: Supersaturation, and patients with persistent low urine volumes:

A Walking Tour – Supersaturation

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.

The Low Flows

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. By the way Joan writes novels – take a look.


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.


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.

Walking Tours

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.

How do We Diagnose Medullary Sponge Kidney?

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.

How Kidney Stones Cause Pain

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.

Jill Harris on Why and How of 24 Hour Urine Collections. 

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.

A Rebuke of the ACP Stone Prevention Guidelines

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.

24 Hour Urine Testing – Supersaturation

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.

CYSTINURIA: An Introduction for Patients

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.

Marriage of Science and Medicine

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.

Citrate and Metastable limits 

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.

How Potassium Citrate Pills Work

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.

Plugs in Kidneys

Between stone attacks, one can forget about the importance of prevention. So much water, pills, and nothing happens. This new post shows very new research done over the past decade or so, mainly by us, which shows that the tiny tubules of the kidneys can become plugged with calcium phosphate crystals. Fortunately kidney function appears to remain intact, but there is cell injury and inflammation. No one knows right now if stone prevention treatments will also prevent these plugs, but since the plugs form at the very ends of the renal tubules, where the final urine exits into the renal pelvis, one would think that whatever reduces crystal formation in the urine will reduce plugging.

How Citrate Inhibits Kidney Stone 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.

Calcium Binding By Citrate

The citrate pills over whose price we haggle and bargain dissolve as we take them, the molecule enters our blood, urine citrate rises, and new stones become less frequent.

This benefit comes from two properties of citrate. It can bind calcium in a very soluble complex so it is not free to bind with oxalate or phosphate to make stones. That is what is in this post. It can slow or even stop the growth of stone crystals. That is in another post yet to be written.

You who take this medication might want to know why it is given and what it does. Here is the first part.

Potassium Citrate Treatment

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.

How Much Fluid Intake Do You Need?

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.

A Taste For Variety

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. 

Price of Potassium Citrate

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 Coke Treatment

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.

How to Drink Water

Neat Tricks

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.

A Reservation

Water is always the first line of treatment for stones.The most important thing to do about supersaturation is lower it, and water will do just that. In relation to kidney stone prevention, more is better. In a perfectly healthy younger (below age 50) person taking no medications, up to 5 or even 6 liters a day is safe provided it is consumed over the whole day and never all at once. But if you have heart disease, kidney disease, or liver disease, or are elderly, great caution is important and the amount of water needs to be determined individually for you. When diuretic drugs are being used, to lower urine calcium excretion for stone prevention or for blood pressure control, water intake needs to be no more than 3-4 liters a day and testing is necessary at intervals to be sure blood sodium levels have not fallen. Many other medications interfere with water excretion; psychoactive drugs can do this, for example. All drugs in use must be reviewed with  your physician before drinking large volumes of water, above 2.5 liters daily. It is true that most people can easily and safely drink the extra water needed for stone prevention, but the reservations are important, always.

What Patients Can Provide

Three crucial things to know about for any patient: kidney stone analysis, the crystals of kidney stones, and supersaturation – the force that drives crystal formation – form the very foundation of stone prevention. These sound like matters for your physician to find out about, but patients are really key in that process.

Prevention of kidney stone formation means prevention of stone crystal formation so you need to know which crystals are forming. The supersaturation in urine for the crystals that are forming is the key to prevention; whatever it is, if crystals are forming it is too high and needs to be lowered. In that statement, is the center of the whole process. Although the process itself is complex, we can easily lose track of, or not see this simple underlying framework. But that framework is important to keep in mind. What are the crystals in stones that are being formed? What are the urine supersaturations with respect to those crystals?

How Can We Tell What the Stone Crystals Are?

Of course we can guess.

X rays offer a clue. People remember what their stones were called, sometimes, but often incompletely because memory is only so good or because they never were told exactly what the stone crystals were. ‘Calcium’ is a common word patients recite me, but calcium oxalate and calcium phosphate have different implications concerning cause of stones and an approach to prevention. Not rarely enough the ‘calcium’ stones turn out to be something really different, like uric acid, or struvite, or some mixture of crystals.

Appearance is helpful for the two organic stones. Uric acid stones are often orange or red because they adsorb urine pigments. But not always. Cystine stones have a lemon yellow tint because they are made of an amino acid. But they are very uncommon, and almost everyone who forms cystine stones has come to know about what they are. Drug stones, stones made out of drugs that crystallize in the kidneys and urine, are very special and sometimes quite dangerous to kidneys but do not look so odd as they are.

We can analyse the stones and keep the report available

The message from all this complexity is simple enough. The means for stone crystal analysis are ready to hand. Vendors abound and the price is not high. The report belongs in your medical record and a copy in your own hands. The former is crucial to inform your physicians. The latter is crucial to inform your physicians when you move, or change doctors, or come to a consultant. The world may become electronic but right now we are far from ‘connected’. The reports you have are yours and can be used to your benefit. Get them, save them, bring them to the physicians who are working toward stone prevention.

We can know about how stones form

The most common stone is made mainly of calcium oxalate. But this kind of stone often forms over an initial deposit of calcium phosphate. When the final stone is analysed the phosphate center can be 5% of the total crystal, seemingly insignificant. Yet it was the beginning of the process. So prevention of that beginning can be a key to success. This is just an example.

How Can We Know the Supersaturations?

Every commercial vendor of 24 hour urine testing for kidney stones provides some estimate of supersaturations. There is no way to know the supersaturation except through urine testing and the 24 hour collection is usual because it given an average over the whole day and night combined. Without 24 hour urine testing, stone prevention has no compass, no measurements to guide treatment. Urine testing is needed at the beginning to know what to do, and during treatment to know if goals are being met. This is true at 6 weeks of treatment and, at least in my way of practicing, every year at least. How else can you know how things are going except to test or to wait and see if more stones form? I prefer the former.


The Posts Are Written for Patients but not Written Down for Patients

Gathered here are posts written specifically for stone forming patients and their families and friends. Every one aims to convey one point, one generally useful fact or action that can improve treatment and prevention of stones. They are not simplified from their scientific and medical origins except in being striped of specialized vocabularies and jargon. Otherwise they convey what science and medicine can offer patients for their own unaided use.

Posts for Physicians and Scientists are also for Patients 

The posts for physicians and scientists are open for all to read. They do use the languages of medicine and science, which is a barrier not usually not insurmountable. Those for patients, though written in common English, still use the generally available words of science. Just as the posts for physicians and scientists are references from the Web, I have found public references for patients, mostly from Wikipedia which, however recondite the topic, are meant to serve the world. In probably all cases where scientific words find their way into the posts, later ones will elaborate on them.

But whether scientific or not, pragmatic seeming or not, everything we will write bears on one main issue: what patients can do with the information to somehow better their condition. There will be never a post without that purpose.

The Posts Will Gradually Build Up a Complete Picture of Stone Disease

The posts are in order of their writing but often link to each other and can be read in any way you wish. We will be adding posts regularly. With time they will map out much of this field of medicine.

We do not view patients as passive recipients of knowledge. They know a lot, have experienced a lot, read a lot, and have a lot to offer concerning this disease. We hope patients and their families will send their comments and opinions. The only limitation is that this site cannot offer any individual medical opinion or advice. We all understand this.

Fredric L Coe MD


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You might say this article culminates the two years this site has been on the web. It is about treatment of the most common stone patients, treatment to prevent more stones, and therefore the topmost important matter for patients and their physicians. The topic is so important I plan three versions. This one is primary, and has not only references but linked documents so original materials are available to everyone. The next will be a video that offers the material in a more fluent if less documented format. Finally Jill Harris has promised to coauthor with me a version in her lovely and popular style. I present all of the treatment trials in the context of the supersaturation hypothesis for stone formation … Continued


This is a three part video about supersaturation, the most unique and critical measurement for evaluation and prevention of kidney stones. Specifically it is about the calcium crystal supersaturations, calcium oxalate and calcium phosphates. The main theme is how supersaturation can be produced and maintained. Urine volume, excretion rates of calcium, oxalate, citrate, uric acid, and urine pH all affect supersaturation and are measured in routine 24 hour urine test panels. We try to prevent stones by altering these excretion rates. But crystals cannot ‘know’ anything about excretion rates, nor about a single concentration, like urine calcium or oxalate. Crystals know only the supersaturation, which reflects the products of calcium and oxalate or calcium and phosphate concentrations. Although we treat excretion rates we really treat supersaturation. … Continued

crystal for article

This is the first of what may become a series of articles done as videos. The site is now a reasonably complete knowledge base but many of the ideas are hard to get and there is a lack of overview materials that are integrative. That is what I plan for these video articles to do. This first one tells about how crystals form and how they form specifically in kidneys to create stones and nephrocalcinosis. It draws upon many of the articles as a base and pulls them together into one narrative. It also adds materials not found anywhere else on the site because best presented in a video format. Please let me know what you think. Regards, Fred Coe … Continued


Unlike Zeus, or Athene, Janus did not come down to the Romans from the Greeks. Instead Janus appears to have originated in myths concerning what may have been an actual person present very early in Roman history and later deified. Janus presided over beginnings and endings, over gateways and doors, and was invariably dual in nature. Like the idiopathic calcium oxalate stone formers, these are people whose stones are composed of calcium crystals and who have no systemic disease as a cause of their stones – therefore ‘idiopathic’ stone formers. But unlike the calcium oxalate stone formers, their stones contain predominantly calcium phosphate crystals. And unlike their more unitary counterpart, calcium phosphate stones can be one of two different kinds – brushhite … Continued

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

A RELIABLE AND PATIENT FOCUSED SITE 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 grown into a wonderful resource for patients. He is a superb stone surgeon and offers patients opportunities to ask questions and also write posts about their own personal experiences. I am impressed with the level of patient involvement, and the strong orientation to the details of their clinical care. From a scientific standpoint I think Dr Nguyen’s site is completely reliable, which is critical for patients and family members who want to be sure what they are reading is as true as science can make it. … Continued


This is the first of a series of articles concerning the stone former phenotypes. ‘Phenotypes’ means literally the types of appearances of stone formers as observed medically, by which is meant observed using the common tests and measurements of medicine. These ‘types’ have value as they constellate abnormalities that might be individually confusing into patterns that can be recognized and that have implications for treatment and prognosis. More precisely, medicine works entirely from abnormalities, meaning departures from what I might call the normative trajectory, the sum of all measurements and characteristics one expects among healthy people as they move through life. The abnormalities of medicine are all departures that produce a state of unwellness, or illness as is more accurately said. … Continued

low salt food

When my husband, Pat, had his first kidney stone, his doctor advised him to “take the salt shaker off of the table.”  He thought that would be easy.  He didn’t consider that every-day foods are packed with sodium. Sticking to a low-sodium diet isn’t easy.  It takes planning. With so many convenience foods available, I feel like a pioneer woman making chicken stock from bones and canning tomatoes to avoid high sodium canned versions. It’s worth it, though. Pat has now attained sodium consumption below the typical non-stone forming American. We’re all hoping this helps him avoid future issues. “Convenience food” has to be homemade when you are on a low sodium diet. This eliminates frozen meals, canned soup, Velveeta,  frozen … Continued

download web app logo

This is an article for all of you to write. The web is awash in apps for tracking fluid intake, and kidney stone prevention is all about fluids. Some ‘smart bottles‘ have arrived on the market. They track what you drink and keep the results on your smartphone. Since some of these are kickstarter efforts there is even an article on Slate about them. Some appear to be finished and rather sleek products. We know nothing about them. There are apps for sodium intake, calcium intake – We think. The field looks thin for calcium apps. Low sodium and high calcium diets are important in stone prevention. We even found one app for preventing kidney stones – see if you can find it. … Continued


Although seemingly devoid of biological importance in humans, oxalate traces a curiously elaborated path in and out of the body. Incidentally, and from time to time, it contributes to calcium oxalate stones, and in extreme instances, to kidney damage and even kidney failure. You have two choices. You can read the article OR you can watch this brief movie which says what is in the article by way of an introduction. The Main Factors The large drawing that heads this article summarizes oxalate movements through the body. What enters the blood is the sum of oxalate produced by the liver plus the amount absorbed from foods, minus the amount transported out of blood back into the gut lumen. What enters the urine is the sum of … Continued