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Kidney Stone Management: A Dietician's Perspective on Passage & Prevention

Author Olivia Reid covers Kidney Stone Management: A Dietician's Perspective on Passage & Prevention on BackTable Urology

Olivia Reid • Oct 28, 2023 • 89 hits

Expert clinical dietician, Dr. Kristina Penniston delves into the intricacies of kidney stone prevention, with a primary focus on the pivotal role of diet and the essential collaboration between urologists and dieticians. The fundamental question of whether patients who have successfully passed kidney stones are at fault is explored. Dr. Penniston's approach, akin to a "diet detective," involves a systematic evaluation that considers diagnostic data, medical history, medication analysis, and a non-judgmental assessment of dietary habits. Strategies for appropriate data collection and evaluation are discussed in an attempt to gain dietary insights with patients. This article features excerpts from the BackTable Urology Podcast. We've provided the highlight reel in this article, and you can listen to the full podcast below.

The BackTable Urology Brief

• Diet plays a nuanced role in the prevention of kidney stones, emphasizing the necessity for a multidisciplinary approach involving urologists and dieticians.

• Practices like consuming Coca-Cola, cod liver oil, taking supplements, or even pushing fluids for hastening the passage of a kidney stone lack substantial scientific support.

• Kidney stone causes can range from genetics to underlying medical conditions and medications, meaning that diet is not always a factor. However, diagnostic data such as 24-hour urine results, blood values, and dietary history are essential in assessing stone risk.

Kidney Stone Management: A Dietician's Perspective on Passage & Prevention

Table of Contents

(1) Bridging the Nutrition Gap in Kidney Stone Management: The Role of Dieticians

(2) Can You Speed Up Kidney Stone Passage? Debunking Common Myths

(3) The Diet Detective Approach: Identifying Kidney Stone Causes & Solutions

Bridging the Nutrition Gap in Kidney Stone Management: The Role of Dieticians

In kidney stone prevention, the critical role of dieticians is often overlooked in healthcare education. Dr. Penniston and Dr. Monga shed light on the underemphasis of nutrition therapy in treating kidney stones and discussed the necessity of urologists collaborating with dieticians. They emphasized that while many healthcare disciplines receive extensive training for conditions like diabetes and cardiovascular diseases, there's a noticeable void in education when it comes to kidney stones. This gap exists despite the complexities involved in kidney stone management. Dr. Penniston explains that most dieticians graduate without a comprehensive understanding of kidney stones and their relationship with nutrition. However, the solution to this issue lies in identifying the right dietician and urologist dynamic. Urologists can reach out to the director of clinical nutrition at their hospital or seek local dieticians for collaboration. It's vital to educate these dieticians, potentially by referring to resources like the Nutrition Care Manual from the Academy of Nutrition and Dietetics, to ensure comprehensive patient care.

[Dr. Manoj Monga]
You mentioned accredited internships. Are there any internships that specialize in kidney stone prevention?

[Dr. Kristina Penniston]
That's a great question. The answer is no. In fact, there's not a whole lot of education that dieticians and prospective dieticians get with respect to treating kidney stones with nutrition therapy. I think this is because there's so much attention placed on the big diseases: diabetes, of course, there's a whole bunch of nutritional strategies for that, cardiovascular disease, and some of the GI diseases. I think this lack is in part because so much attention is focused on that, but also because I think kidney stones are complicated. I'm not sure that that's an excuse for why it's not taught. All I know is that most dieticians come out of their programs without ever having learned anything about kidney stones and nutrition.

[Dr. Manoj Monga]
If one of our urologists in the audience was hoping to start a clinic with a dietician as their partner, how would one identify that individual, and how would one help educate or fill the gaps in the education that might have been there during their schooling?

[Dr. Kristina Penniston]
First, I really hope that urologists do look for dieticians to partner with. I know from hanging around urologists for so many years that there's not enough time in a day for a urologist who's got a busy clinic and a busy surgical practice to do the kind of therapy that's really needed. Even me, I see a lot of patients in a day, but not as many as a urologist does, so I still have time to do the counseling.

I would say that a urologist should look in his or her hospital and make contact with the director of clinical nutrition. All hospitals are required to have registered dietician/nutritionists as part of their accreditation with JCAHO. Now, not all hospitals have to have outpatient dieticians, which is probably what you would want in a stone clinic, but many do. In fact, many of the academic settings, where probably some of the audience members are, have more than enough dieticians to meet their minimum requirements.

There may be some available FTE. If you go to your clinical nutrition director and say, "Hey, I've got this stone clinic. It's multidisciplinary. Here's all the evidence for the role of nutrition therapy. I would really keep this person busy. Let's work on that." That's one idea. If that doesn't work, and typically it doesn't because there's not as many dieticians as there are a need for, then I would suggest finding a local dietician to whom you could refer your patients. In both cases, whether you get one in hospital or find one in the community, you're undoubtedly going to have to expose that dietician to education, if not educate him or her yourself, look for some sources to do that.

There are sources. There's a lot of publications and a manual that we use in the Academy of Nutrition and Dietetics called the Nutrition Care Manual. There's a chapter there about kidney stones and nutrition. Those are two suggestions that I have for getting a dietician for your practice. The only other way is to actually include a dietician and reimburse that dietician through your practice. This may not be appealing, but as you may or may not know, dieticians are not reimbursed for most of the nutrition therapy services that we provide by Medicare, and so a lot of what we do is considered value-added.

Listen to the Full Podcast

Dietary Modifications for Kidney Stone Prevention with Dr. Kristina Penniston on the BackTable Urology Podcast)
Ep 104 Dietary Modifications for Kidney Stone Prevention with Dr. Kristina Penniston
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Can You Speed Up Kidney Stone Passage? Debunking Common Myths

Dr. Monga and Dr. Penniston tackle popular but often misguided approaches to facilitate the passage of kidney stones. Patients frequently come in with notions about drinking a liter of Coke, taking cod liver oil, or other unverified methods that they've discovered on the internet. Dr. Penniston points out that while many patients claim success with pushing fluids while passing a stone, the scientific evidence supporting this practice remains limited. In essence, the act of hydrating during stone passage is a good instinct but may not significantly expedite the process. As for the use of Coca-Cola, cod liver oil, or supplements to hasten stone passage, Dr. Penniston highlights that there is no substantial scientific backing for such practices.

[Dr. Manoj Monga]
Dr. Penniston, no question, it is value-added, but it sounds like there are a few other logistics to work around. In the interim, maybe let's see what knowledge we can share with our audience today. Perhaps we'll start with not prevention but stone passage. Patients often come in and say, "I saw on the internet I'll drink a liter of Coke or I'll do some cod liver oil." A variety of things that I suspect have been tested with time, but maybe not with science. Are there any things that you've heard of that may actually work to help kidney stones pass?

[Dr. Kristina Penniston]
Not many things. Unfortunately, even the idea of pushing fluids while passing a stone, while many of my patients say that that's what helps them pass stones, there actually isn't the best evidence for that that it’s actually going to hasten kidney stone passage. I think it would be a good instinctual thing to do when you're trying to pass a stone, but drinking Coca-Cola, taking cod liver oil, doing any kind of supplements or anything like that to hasten passage, there's no evidence.

The Diet Detective Approach: Identifying Kidney Stone Causes & Solutions

Dr. Penniston shares her unique approach to guiding patients who have recently passed a kidney stone and are eager to understand how to prevent future occurrences. She reassures patients that passing a stone is not indicative of a personal failing; it's important to recognize that not all stones are a result of dietary choices. Dr. Penniston emphasizes the complexity of kidney stone formation, which can be influenced by genetics, underlying medical conditions, medications, and a combination of these factors. She described her role as that of a "diet detective" and discussed the comprehensive approach employed. This approach includes examining diagnostic data like 24-hour urine results and blood values, along with a thorough medical history, medication assessment, and a detailed dietary analysis. Dr. Penniston strives to determine whether diet plays a significant role in a patient's stone risk, even if it may not be the sole cause. She works to foster an environment of respect and openness, allowing patients to share personal dietary habits without fear of judgment, as these habits can be crucial in understanding kidney stone prevention.

[Dr. Manoj Monga]
The patient fortunately has passed their stone. They're in the clinic now saying, "What did I do wrong? How do I prevent the next one?" What do you say?

[Dr. Kristina Penniston]
My first comment is going to be: you didn't do anything wrong. Many times, diet is not the reason the patient formed the stone. I like to point that out because I think it manages patients' expectations. I think if we insist on blaming the patient or trying to find a dietary cause for every type of stone and every patient's stone, we're going to miss the mark. Not all stones are caused by diet, many are caused by genetics, many are caused by underlying medical conditions that have systemic influences that predispose one to stones, some are caused by medications, and probably most are caused by a combination of all of those things. I like to tell the patient, "You didn't do anything wrong, but there might be something we can optimize or something we can improve in the diet."

What I consider myself is sort of a diet detective, if you will. The patient comes to me, they probably passed their stone as you said or had surgery. One of the first things I want to do is try to figure out if diet even likely contributes to their stone risk. The way I do that is by looking at all the same diagnostic things that a urologist does. I'll look at 24-hour urine results. I'll look at relevant blood values. I'll look at medical history and medications. Then, I also do a very comprehensive diet assessment. Over the years, I've developed a stone-targeted assessment, if you will. Given that there are many types of stones, more than just calcium, for example, and given that there are many different risk factors, there can be a lot of things to explore. I like to consider myself the detective that's either ruling in or out a dietary cause for stones. Often I can find something, like I said earlier, to improve, even if I'm not convinced it was the actual reason they formed the stone.

[Dr. Manoj Monga]
Does the detective work take a formal structure in terms of dietary logs or recall? Then, the other question would be for the individual who perhaps doesn't want to do a 24-hour urine collection, are there empiric recommendations that you would recommend for everyone?

[Dr. Kristina Penniston]
Right, I'll take the second question first. There's a lot of debate about whether a 24-hour urine collection should just be one or whether it should be more than one, and whether it's really effective or useful. I think it is. I think that the real power of it though is in monitoring the effects of therapy over time. I do think it's useful for patients to do a 24-hour urine collection and hopefully, it won't be their one and only because you'll want to test how your therapy is working on their risk parameters. If a patient doesn't want to do it, or if their insurance won't cover it, or if the urologist simply doesn't think it's necessary, I can still do a lot. I can still do a very targeted diet assessment.

I will sometimes ask people to bring in diet logs, but there are some pitfalls to that. Any dietician listening might relate to this. When you tell a patient beforehand that you're going to be looking at certain things in their diet or that you're going to even just be looking at their diet, they will often change how they eat. I could say, "Manoj, here's this diet log, spend three days filling it out, and then we'll talk about it when you see me next." I've already planted in some patients' minds some terror there, like they're going to get in trouble with the dietician if they admit what they ate, so I don't do that very often.

What I like to do is on-the-spot; I like to query the patient in a couple different ways. I'll query them about what they ate over the last two days, if they can recall, and then I'll ask some very targeted questions about how they habitually eat. For example, based on the information I got from the 24 or 48-hour recall, I might say things like, "In a typical week or in a typical month, how many times do you have X?" Then I go through my list, and I'm able to piece things together. What I really want is a picture of their habitual diet. I don't even really want to know so much about how they ate on the day of their urine collection because that too is something patients will alter their behavior for when they do that. I really like to get an on-the-spot, no predispositions, no fear, and also, dieticians can relate to this.

I think urologists, it's good for them to know this. For many patients, diets are very personal, how they eat is really personal, and their dietary habits. You want to try to get it, things that they don't want to admit to you and things that they feel guilty about and you want to get portion size. None of that is possible if the patient feels you're going to judge them. It's really important, and dieticians are especially equipped to do this, to give the patient the space and the feeling that he or she is respected no matter what they say because you always want the truth and not just something that they want you to hear. Those are some strategies that I have found useful.

Podcast Contributors

Dr. Kristina Penniston discusses Dietary Modifications for Kidney Stone Prevention on the BackTable 104 Podcast

Dr. Kristina Penniston

Dr. Kristina Penniston is a clinical nutritionist specializing in therapy for patients with urologic diseases.

Dr. Manoj Monga discusses Dietary Modifications for Kidney Stone Prevention on the BackTable 104 Podcast

Dr. Manoj Monga

Dr. Manoj Monga is the chair of the urology department at UC San Diego in California.

Cite This Podcast

BackTable, LLC (Producer). (2023, June 28). Ep. 104 – Dietary Modifications for Kidney Stone Prevention [Audio podcast]. Retrieved from

Disclaimer: The Materials available on are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.



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