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Michael Smith, MD (Host):  Urine contains many dissolved minerals and salts. When your urine has high levels of these minerals and salts, you can actually form stones. Kidney stones can start small but can grow quite large in size. Welcome The GW HealthCast. I’m Dr. Mike Smith and today’s topic Understanding Kidney Stones. My guest is Dr. Patrick Mufarrij. Dr. Mufarrij is a urologist an Assistant Professor with the George Washington University School of Medicine and Health Sciences and is affiliated with The George Washington University Hospital. Dr. Mufarrij, welcome to the show.

Patrick Mufarrij, MD (Guest):  Thank you for having me.

Host:  So, why don’t we start off – can you explain to us exactly what kidney stones are?

Dr. Mufarrij:  Absolutely. So, kidney stones are essentially concretions or crystals that form in the urine, similar to how snowflakes form during a snowstorm; stones form crystals first which then coalesce together to form larger stones. And it is simply a matter of saturation or how concentrated the urine is. If someone drinks a lot of fluids, makes a lot of urine and the urine is dilute; then these crystals will not form. Similarly, if you threw a handful of salt into a swimming pool; it would just dissolve. However, if someone does not make a lot of urine; then these crystals will form very, very likely to form similarly to throwing a handful of salt into a little cup. So, there are a lot of crystallization processes involved but also one of the main driving forces is the concentration.

Host:  So, when you say that, so who is at risk then? Why would somebody’s urine be so concentrated?

Dr. Mufarrij:  Well, a lot of it is determined based on the environment that people live in, their genetics and then potentially the anatomy of their kidneys. So, for instance, if someone has several relatives that have had kidney stones; there is likely some genetic predisposition for them to form stones. Environment also plays a role in the sense that we know that in southern states, or states in which there is more heat; stones form more commonly. And this is presumed to be due to the fact that there’s just – the temperature itself causes people to sweat. And then in terms of the anatomy, some people do have aberrant drainage systems of their kidneys, and if the kidney is not draining briskly; the stagnation of urine can cause the formation of stones.

Host:  Right. Now most people, if they have some sort of kidney anomaly, some sort of deformity, most people know about that or are there some people who develop stones and that’s when you discover that there was an abnormal kidney?

Dr. Mufarrij:  Without question. We see so many patients whose first stone event elucidates the fact that they have some sort of abnormality of their kidney. That being said, there’s also several patients who we take care of who have known issues with their kidney and we keep an eye on them so that they don’t form kidney stones. But it’s very common for people to present with their first stone event and then after a workup we identify the reasons and one of them could be that their kidney is a little bit different.

Host:  So, genetics, environment and maybe an abnormal kidney are the primary risk factors for developing stones. When somebody does develop a stone; are there always symptoms and if there are symptoms, what are they?

Dr. Mufarrij:  So, not always are there symptoms. It depends on the location of the stone. Most stones that pass into the ureter which is the small tube that connects the kidney to the bladder; most of those stones will result in immediate symptoms. And patients describe this situation as probably the worst pain of their life. Women will say it’s worse than childbirth and men will say it’s worse than anything that they’ve ever had. Stones, however, can also lay in the kidney itself which is a larger space than the ureter. And a lot of times these stones in the kidneys don’t cause the agonizing pain that the stones in the ureters do simply because there’s just more space to float around. Now sometimes patients will say you know I have a vague pain in my flank and you end up finding they have a small stone in their kidney. That’s not uncommon. But when you talk about the classic kidney stone pain; it’s always when the stone is in the ureter.

Host:  Now if you come across somebody that had maybe some of that dull pain on their side towards the back and you do an ultrasound, I think that’s usually a common procedure, right so you do an ultrasound and you see the stone there; what do you do at that point? Does it depend on if – what the pain is like? Are you always going to treat that? What would be your approach to finding a kidney stone?

Dr. Mufarrij:  So, without question if someone has symptoms, vague symptoms and they are not in agonizing pain, then you can certainly start with an ultrasound which is non-radiating and pretty easy and inexpensive to perform which gives you some general information. If you have identified that there is a suggestion of a stone; then oftentimes the next step would be getting a CAT scan so that you can understand distinctly and definitively how much stone, where the stone is. A CAT scan without contrast is a radiating source of imaging, but it is also the most perfect imaging to understand kidney stones in the human body.

And in terms of whether or not you treat stones; definitely it depends on symptoms. If patients are experiencing symptoms that are incompatible with their quality of life desires; then absolutely you would offer them a surgical procedure. If their kidney is obstructed, if they are developing infection, at the same time, these are all reasons to intervene before things get worse. Now a lot of times, we detect stones that are simply discovered accidentally or discovered and are not causing severe problems at all. In these scenarios, we basically tell the patient that they could elect for treatment of this stone or these stones before they become a problem or more often than not what we do is we perform a metabolic evaluation first to understand the mechanisms that cause their stones to form and once we have a handle on what’s causing the stones to form; we make recommendations dietarily or we add medicines or vitamins to their diet to mitigate those risk factors and then we offer them stone removal at that time. But we also have a lot of patients who just don’t want surgery unless they absolutely need it, which is reasonable and for those patients, we survey their stones by getting an ultrasound or an x-ray in order to understand if it’s growing any larger or if any new stones are forming.

Host:  You mentioned diet there in your explanation that in some people maybe there is a stone, maybe the pain is not so bad. In that case, what are those dietary suggestions that you make to make sure that stone doesn’t get any bigger or more stones form?

Dr. Mufarrij:  Well first and foremost, it’s all – likely the biggest risk factor for stone formation is the amount of urine that someone makes. Meaning if you are dehydrated, crystals will form. In the business we have a saying that the solution to pollution is dilution. So, you need to dilute the urine by drinking more fluid and people always ask what kind of fluid. Mostly anything except for a couple – there are a couple of fluids that are a little bit dangerous for kidney stones. One of them is tea. Most teas except for green tea and herbal teas, most teas have a fair amount of oxalate so, drinking a gallon of sweet iced tea a day or drinking a lot of tea a day is definitely something that can increase the amount of oxalate in someone’s urine and I’ll get to oxalate in a second. Because when you talk about diet and kidney stones in America; there has to be a conversation about oxalate which is not something people have heard a lot of unless you have had a stone.

So, first and foremost is the amount of fluid you take in and as I mentioned tea is something you don’t want to drink a lot of, but alcohol, coffee is totally fine in moderation. The other group of drinks that you want to avoid are those with high fructose corn syrup because there is some evidence that that can increase the amount of calcium that enters your kidney when you drink those frequently and also, they are unhealthy generally speaking. But aside from those, you can drink water, water with lemon. A lot of people like adding lemon or citrus to their fluids because citrate which comes from citrus fruits is a natural inhibitor of stone formation. So, you see a lot of people that may be drinking lemonade or adding lemon or lime to their fluids and that’s the reason.

And in terms of the other things dietarily, getting back to oxalate. Oxalate is something that is – it’s a substance that is present in almost every fruit and vegetable and in America, we consume oxalate in large quantities because spinach, nuts, beets, rhubarb, bran, swiss chard, dark chocolate; these are things that have very high quantities of oxalate in a single serving. And these are – the substances that I listed are very common food choices that we make in this country. So, oxalate is one of the main driving forces of stone formation in this country because 80% of stones in this country are calcium oxalate. So, when you eat a lot of oxalate foods, that puts you at increased risk of oxalate entering your kidney where it can complex with calcium. And the distinction here is that calcium is always present in your kidney because the body does not use all the calcium that’s in the bloodstream. It sends a lot of it to the urine to be disposed of. But oxalate is something that can be present in very small quantities in the urine unless you eat a lot of it or have some sort of condition that makes it increased. So, that’s really the rate limiting step in calcium oxalate crystal formation is the oxalate.

Host:  Okay. So, hydrate and we have to watch some of those foods you listed. If you are eating a lot of this – a lot of people eat spinach, right, that’s a big one. So, I don’t think a lot of people know that that is high in oxalate and if you are at risk for stones –

Dr. Mufarrij:  Without question. I’m sorry I didn’t mean to cut you off. Go ahead.

Host:  No, and I was just going to say so a lot of people I don’t think realize some of those oxalate foods. So, we need to hydrate. We need to watch our intake of the oxalates if we are going to handle in a dietary sense the development of stones. Do you find this to work if you have somebody with a small stone, the pain seems to be controlled, you get them to hydrate, you decrease their intake of oxalates; does that, in your experience work?

Dr. Mufarrij:  It does work for a lot of patients that are able to maintain the regimen that we recommend. There are several other dietary factors involved which may beyond the scope of this podcast but one of the things I wanted to mention is the urban myth that calcium should be avoided in the diet. And for years, people would tell stone formers that they should avoid calcium and what ended up happening is these people would literally avoid eating anything with calcium or dairy products or cheese and the problem that that created was – and this was demonstrated in a very elegant study out of Italy. The problem that that created was that without calcium in your intestinal tract; even small amounts of oxalate that are consumed would enter the kidney because there would be no calcium to bind the oxalate in the intestinal tract. So, calcium oxalate can obviously bind anywhere, and you want them to bind in the intestinal tract.

Host:  And that makes sense so then you are getting – you are eliminating the oxalate out your digestive system avoiding the kidney all together. So, you do want to take in some calcium then.

Dr. Mufarrij:  Yes, absolutely. And it’s recommended to take three or four calcium – dietary calcium sources a day meaning from food not from supplements. And that’s about 1000-1200 milligrams of calcium a day which is what’s recommended. But to get back to your question, if you give people the dietary modifications, the general advice given to all stone patients, assuming they have a run of the mill calcium oxalate stone; most of these people will be fine and will be able to control their disease to some extent.

I will tell you this though, stone recurrence rates are up to 80% after ten years of the first stone event. So, if you have a stone attack today, within ten years, you are likely to have another stone attack if you do nothing different. So, it’s important to make whatever interventions as a patient that you do to make those durable interventions because this is something that clearly if you made a stone in the first place, this is something that can come back. And they often do, because people often forget about the pain that occurred with the stone or just simply get potentially lose sight of the importance of maintaining these as dietary lifelong lessons.

Now the other aspect of the regimen, sort of the advice to help prevent stones is the metabolic workup which I touched on earlier. And this simply is just a term we use for getting special blood tests and having patients do special urinary tests because a lot of times people will have unknown risk factors for stones that would only be identified if they do the metabolic testing. And so, for most patients that we see that want a thorough understanding of their stone risk, they do go ahead and do the bloodwork and the urine testing.

Host:  Got you. Yeah, so, I think that’s great. So, we have hydration, we have some dietary suggestions you gave us, a metabolic workup. The good news is if we do follow these things, I think you are saying that this is something that can be controlled and prevented down the line. Dr. Mufarrij, let’s end with this. Why don’t you tell us what you would like my audience to know about kidney stones?

Dr. Mufarrij:  Well kidney stones have been around since the earliest times. It’s mentioned in the Hippocratic oath that we as doctors take. And when you look at the rates of kidney stones in this country, we are talking about nearly 10% of the population has had a kidney stone or will have a kidney stone. So, with that amount of people having kidney stones, with that prevalence rate plus the risk of recurrence of these stones; it’s a very significant health problem from a socioeconomic standpoint. And so I think for those patients that are at risk of kidney stones; they obviously don’t want to have another one again because they are uncomfortable but they should find hope in knowing that this is one disease that you can certainly control if you are willing to understand some basic physiologic principles of your body and if you are willing to be as good as you can be regarding your stone prevention regimen.

Host:  Got you. Dr. Mufarrij, I want to thank you for the work that you are doing and also thank you for coming on the show today. You're listening to the GW Healthcast. Please visit GWDocs.com to get connected with Dr. Mufarrij or another provider, or call 1-888-4GW-DOCS to schedule an in-person or virtual appointment.