Kidney stones in children have been on the rise for more than a decade, mostly due to hypercalciuria and hypocitraturia.
Join us as Uri Alon, MD, Director of the Bone and Mineral Disorders Clinic at Children’s Mercy Kansas City, discusses what is behind the increasing incidence of kidney stones, and medical and non-pharmacological interventions to prevent new stones and inhibit the growth of existing ones.
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Kids and Kidney Stones
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Learn more about Uri Alon, MD
Uri Alon, MD
Uri Alon, MD, is a pediatric nephrologist and Director of the Bone and Mineral Disorders Clinic at Children’s Mercy Kansas City and Professor of Pediatrics, University of Missouri Kansas City School of Medicine. He received his medical degree at Hebrew University, Hadassah School of Medicine, Jerusalem, Israel. He completed a residency in pediatrics at Rambam Medical Center, Haifa, Israel and a fellowship in Pediatric Nephrology at Medical College of Virginia, Richmond, Virginia.Learn more about Uri Alon, MD
Transcription:
Kids and Kidney Stones
Dr. Michael Smith (Host): Our topic today is kids and kidney stones. My guest is Dr. Uri Alon. Dr. Alon is a Pediatric Nephrologist and Director of the Bone and Mineral Disorders Clinic at Children's Mercy Kansas City. Dr. Alon, welcome to the show.
Dr. Uri Alon, MD (Guest): It's nice to be with you this morning.
Dr. Smith: So kidney stones in kids, how common is this?
Dr. Alon: Well we definitely have seen a significant increase in the incidents and prevalence of kidney stones. I remember the days I was a resident, thirty-four years ago, and we rarely saw a child with kidney stones. It was a rarity. And multiple studies- and we've seen a significant increase. In multiple studies, including from our own institution, but also from other places in the United States and other places in the world, showed about an increase in incidents by a factor of three to four.
Dr. Smith: Wow.
Dr. Alon: And with that, also increasing prevalence.
Dr. Smith: So what do we think is going on there? Why are we seeing such an increase?
Dr. Alon: Well we felt that a factor might be improved imaging studies used in the emergency department like the more common use of ultrasounds, or CT, but then we realized there are other factors. There has been no change in the genetic pool and genetics does play some role, we have to assume that this is environmental, and indeed we were able to detect two main factors in the environment which may have resulted in this increase. One is the global warming and the other is nutrition - changes in nutrition.
Dr. Smith: So global warming right there, that caught my attention, tell me the connection there. What do you think is going on?
Dr. Alon: We think as the world gets hotter, this may have an influence, in fact this may result in some degree of dehydration, and I will give you a very simple example related to the United States Army in Iraq. They noticed an increase in incidents of kidney stones among the soldiers, and once an order went to the soldiers to increase fluid intake, there was a decrease in incidents of kidney stones. So just changes in the environment had a response to that. And we know also in the United States there is the Sun Belt in the southern United States where the incidents always has been higher. So environmental factors, temperature, humidity, fluid intake do have a role here.
Dr. Smith: You also mentioned nutrition, too. So let's talk a little bit about that. What role does nutrition play in the development of kidney stones?
Dr. Alon: It has been known for awhile, and we have shown it in our pediatric population as well, is that the association between salt intake and kidney stones. We have to keep in mind physiologically that 97% of sodium and potassium that we take in our nutrition are absorbed within the gut. So this means they also have to find a way out through the urinary system. We also know that sodium in the urine drags calcium with it, namely more sodium in the urine, more calcium in the urine. So if we eat more salt, we end up with more sodium in the urine, and with then more calcium in the urine. So as the amount of calcium increases, there would be a tendency to form crystals either of calcium oxalate or calcium phosphate, the crystals will continue to grow and eventually will end up with formation of stones. On the other hand, potassium has the opposite effect. The more potassium in the urine, the less calcium in the urine. We think that when we eat more potassium, whether it's potassium itself, or the anion that goes with it, whether it's citrate or other anions, result in more calcium being directed to the bones, rather to the urine. So when it comes to nutrition, what we know is that we all eat too much salt on one hand, and not enough fruit and vegetable, which are the source of potassium on the other. That's where nutrition gets-
Dr. Smith: Yeah and so one of the things obviously I know Children's Mercy has been doing a lot more educating children and their families. When you go grocery shopping, make sure you're shopping in those outside aisles where the fruits and vegetables are. We're shopping way too much in those middle aisles, right? Where all that processed sodium and processed food is at, so that's playing a role. So that's interesting, so global warming and nutrition definitely do play a role. When you look at- how about a nice just review, Dr. Alon, of the common causes? We know again nutrition plays a role, but what are some of the other common causes out there of kidney stones in kids?
Dr. Alon: Alright so we did a study with our friends in Brazil, and we analyzed data on 220 children in adolescence with kidney stones, and we looked what would be the reasons for the development of kidney stones. And the most common reason was, as I mentioned earlier, not generating enough urine, namely the urine is too concentrated, and this is due to the fact that the patients don't drink enough, and that's number one. Reason number two is excess calcium in the urine, hypercalcemia. And I already mentioned the reason I believe, it might be the case in a few cases it might be genetic, we find a history of kidney stones in one of the parents, so it might be autosomal dominant, and this could definitely be a factor, but in the majority again it's environmental. And the third reason is hypocitraturia, namely not enough citrate in the urine. Now keep in mind, citrate is the good stuff in the urine. Citrate in the urine combines with calcium, it combines with calcium, it keeps it soluble, so it's soluble salt, so citrate in the urine basically lowers the risk for formation of kidney stones. And there if there is not enough citrate in the urine, again the tendency is to develop kidney stones. And what is the source of citrate? Again, we go back to nutrition, diet. Citrate, as the name implies, citrus comes from fruits and vegetables.
Dr. Smith: Right.
Dr. Alon: So one more time. And just to give you an idea, the recommendation for intake of fruits and vegetables is five to six servings a day. The American teenager on average takes 1.4 services per day, so we have a big way to go to achieve the goal.
Dr. Smith: So once you diagnose kidney stones in a kid, what's the preferred treatment?
Dr. Alon: So once a stone was detected, and in previous days we were able to capture many of these stones and analyze the chemistry. Now it's become less common, and what we routinely do is to ask the patient to have a twenty-four hour urine collection, and then we analyze both the volume and the chemistry. And again, the most common epidemiology in children as I mentioned is besides low volume hypercalciuria. And we also measure at the same time the amount of sodium and potassium, and usually the first step would be non-pharmacologically intervention. We try to minimize the use of medication in these children and teenagers. So the non-pharmacological intervention we conclude higher intake of fluid, if necessary we would give a note to school to allow a child to carry a bottle of water or other fluids. And then when it comes to nutrition, basically we have here a very good guideline provided by the DASH diet. Now the DASH diet was developed for adults with hypertension, and DASH stands for dietary approach to stop hypertension. And that basically- I don't even call it a diet, I call it healthy nutrition. It includes less fat, more fiber, and from our standpoint less salt and more fruits and vegetables. So that's what we recommend. High fruit intake and the DASH diet. And then several weeks later, six to eight weeks later, we repeat the twenty-four hour urine collection, see whether this kind of intervention achieved the goal, or whether we have to do another adjustment on the nutrition. And if despite this- and this basically is effective in about 50% of patients.
Dr. Smith: Right, that's what I was just going to ask.
Dr. Alon: Yes and in the others, we may need to apply pharmacologic intervention. And this basically is based on two or one medicine, thiazide diuretics which have been used for more than fifty years now especially in adults, but we use them also in children to decrease urine calcium. And in other cases we use potassium citrate supplementation. And basically potassium citrate, as the name implies, it's potassium citrate so it's a supplement, it's not a foreign chemical, it adds potassium and citrate to the dietary intake, and hopefully that we'll change the urine chemistry.
Dr. Smith: So Dr. Alon, what role should primary care providers play in treating kidney stones?
Dr. Alon: I would say that the main role as I see it for primary care physicians, and society as a whole, and even politicians as well, but again mostly primary care physicians, is to guide the family about healthy nutrition. And this is important not only for prevention of kidney stones. We know that it has many other beneficial effects, whether it's maintaining normal blood pressure, we know that it has a positive effect on the skeleton, and a recent study showed that it may even improve some mental functions.
Dr. Smith: Right.
Dr. Alon: So again, I don't even call it a diet. I call it healthy nutrition, and I would recommend that not only the child would follow it, but the whole family. It's much easier if mother cooks the same kind of low-salt food. And when you say 'low,' it's a bit misleading. If the salt's within the frame of the recommendation, it's just that we all eat too much salt, so we just need to cut it back to the recommended dose. And if the whole family does it, I think it's easier also for the child to because of the family and benefit from it.
Dr. Smith: Dr. Alon, I like that idea of it's moving away from that word 'diet,' right? Because I think that has some negative connotation for people and it's really about a lifestyle and healthy nutrition, as you say. Dr. Alon, thank you for the work that you're doing at Children's Mercy, and thank you for coming on the show today. You're listening to Pediatrics in Practice with Children's Mercy Kansas City. For more information, you go to www.ChildrensMercy.org. That's www.ChildrensMercy.org. I'm Dr. Mike Smith, thanks for listening.
Kids and Kidney Stones
Dr. Michael Smith (Host): Our topic today is kids and kidney stones. My guest is Dr. Uri Alon. Dr. Alon is a Pediatric Nephrologist and Director of the Bone and Mineral Disorders Clinic at Children's Mercy Kansas City. Dr. Alon, welcome to the show.
Dr. Uri Alon, MD (Guest): It's nice to be with you this morning.
Dr. Smith: So kidney stones in kids, how common is this?
Dr. Alon: Well we definitely have seen a significant increase in the incidents and prevalence of kidney stones. I remember the days I was a resident, thirty-four years ago, and we rarely saw a child with kidney stones. It was a rarity. And multiple studies- and we've seen a significant increase. In multiple studies, including from our own institution, but also from other places in the United States and other places in the world, showed about an increase in incidents by a factor of three to four.
Dr. Smith: Wow.
Dr. Alon: And with that, also increasing prevalence.
Dr. Smith: So what do we think is going on there? Why are we seeing such an increase?
Dr. Alon: Well we felt that a factor might be improved imaging studies used in the emergency department like the more common use of ultrasounds, or CT, but then we realized there are other factors. There has been no change in the genetic pool and genetics does play some role, we have to assume that this is environmental, and indeed we were able to detect two main factors in the environment which may have resulted in this increase. One is the global warming and the other is nutrition - changes in nutrition.
Dr. Smith: So global warming right there, that caught my attention, tell me the connection there. What do you think is going on?
Dr. Alon: We think as the world gets hotter, this may have an influence, in fact this may result in some degree of dehydration, and I will give you a very simple example related to the United States Army in Iraq. They noticed an increase in incidents of kidney stones among the soldiers, and once an order went to the soldiers to increase fluid intake, there was a decrease in incidents of kidney stones. So just changes in the environment had a response to that. And we know also in the United States there is the Sun Belt in the southern United States where the incidents always has been higher. So environmental factors, temperature, humidity, fluid intake do have a role here.
Dr. Smith: You also mentioned nutrition, too. So let's talk a little bit about that. What role does nutrition play in the development of kidney stones?
Dr. Alon: It has been known for awhile, and we have shown it in our pediatric population as well, is that the association between salt intake and kidney stones. We have to keep in mind physiologically that 97% of sodium and potassium that we take in our nutrition are absorbed within the gut. So this means they also have to find a way out through the urinary system. We also know that sodium in the urine drags calcium with it, namely more sodium in the urine, more calcium in the urine. So if we eat more salt, we end up with more sodium in the urine, and with then more calcium in the urine. So as the amount of calcium increases, there would be a tendency to form crystals either of calcium oxalate or calcium phosphate, the crystals will continue to grow and eventually will end up with formation of stones. On the other hand, potassium has the opposite effect. The more potassium in the urine, the less calcium in the urine. We think that when we eat more potassium, whether it's potassium itself, or the anion that goes with it, whether it's citrate or other anions, result in more calcium being directed to the bones, rather to the urine. So when it comes to nutrition, what we know is that we all eat too much salt on one hand, and not enough fruit and vegetable, which are the source of potassium on the other. That's where nutrition gets-
Dr. Smith: Yeah and so one of the things obviously I know Children's Mercy has been doing a lot more educating children and their families. When you go grocery shopping, make sure you're shopping in those outside aisles where the fruits and vegetables are. We're shopping way too much in those middle aisles, right? Where all that processed sodium and processed food is at, so that's playing a role. So that's interesting, so global warming and nutrition definitely do play a role. When you look at- how about a nice just review, Dr. Alon, of the common causes? We know again nutrition plays a role, but what are some of the other common causes out there of kidney stones in kids?
Dr. Alon: Alright so we did a study with our friends in Brazil, and we analyzed data on 220 children in adolescence with kidney stones, and we looked what would be the reasons for the development of kidney stones. And the most common reason was, as I mentioned earlier, not generating enough urine, namely the urine is too concentrated, and this is due to the fact that the patients don't drink enough, and that's number one. Reason number two is excess calcium in the urine, hypercalcemia. And I already mentioned the reason I believe, it might be the case in a few cases it might be genetic, we find a history of kidney stones in one of the parents, so it might be autosomal dominant, and this could definitely be a factor, but in the majority again it's environmental. And the third reason is hypocitraturia, namely not enough citrate in the urine. Now keep in mind, citrate is the good stuff in the urine. Citrate in the urine combines with calcium, it combines with calcium, it keeps it soluble, so it's soluble salt, so citrate in the urine basically lowers the risk for formation of kidney stones. And there if there is not enough citrate in the urine, again the tendency is to develop kidney stones. And what is the source of citrate? Again, we go back to nutrition, diet. Citrate, as the name implies, citrus comes from fruits and vegetables.
Dr. Smith: Right.
Dr. Alon: So one more time. And just to give you an idea, the recommendation for intake of fruits and vegetables is five to six servings a day. The American teenager on average takes 1.4 services per day, so we have a big way to go to achieve the goal.
Dr. Smith: So once you diagnose kidney stones in a kid, what's the preferred treatment?
Dr. Alon: So once a stone was detected, and in previous days we were able to capture many of these stones and analyze the chemistry. Now it's become less common, and what we routinely do is to ask the patient to have a twenty-four hour urine collection, and then we analyze both the volume and the chemistry. And again, the most common epidemiology in children as I mentioned is besides low volume hypercalciuria. And we also measure at the same time the amount of sodium and potassium, and usually the first step would be non-pharmacologically intervention. We try to minimize the use of medication in these children and teenagers. So the non-pharmacological intervention we conclude higher intake of fluid, if necessary we would give a note to school to allow a child to carry a bottle of water or other fluids. And then when it comes to nutrition, basically we have here a very good guideline provided by the DASH diet. Now the DASH diet was developed for adults with hypertension, and DASH stands for dietary approach to stop hypertension. And that basically- I don't even call it a diet, I call it healthy nutrition. It includes less fat, more fiber, and from our standpoint less salt and more fruits and vegetables. So that's what we recommend. High fruit intake and the DASH diet. And then several weeks later, six to eight weeks later, we repeat the twenty-four hour urine collection, see whether this kind of intervention achieved the goal, or whether we have to do another adjustment on the nutrition. And if despite this- and this basically is effective in about 50% of patients.
Dr. Smith: Right, that's what I was just going to ask.
Dr. Alon: Yes and in the others, we may need to apply pharmacologic intervention. And this basically is based on two or one medicine, thiazide diuretics which have been used for more than fifty years now especially in adults, but we use them also in children to decrease urine calcium. And in other cases we use potassium citrate supplementation. And basically potassium citrate, as the name implies, it's potassium citrate so it's a supplement, it's not a foreign chemical, it adds potassium and citrate to the dietary intake, and hopefully that we'll change the urine chemistry.
Dr. Smith: So Dr. Alon, what role should primary care providers play in treating kidney stones?
Dr. Alon: I would say that the main role as I see it for primary care physicians, and society as a whole, and even politicians as well, but again mostly primary care physicians, is to guide the family about healthy nutrition. And this is important not only for prevention of kidney stones. We know that it has many other beneficial effects, whether it's maintaining normal blood pressure, we know that it has a positive effect on the skeleton, and a recent study showed that it may even improve some mental functions.
Dr. Smith: Right.
Dr. Alon: So again, I don't even call it a diet. I call it healthy nutrition, and I would recommend that not only the child would follow it, but the whole family. It's much easier if mother cooks the same kind of low-salt food. And when you say 'low,' it's a bit misleading. If the salt's within the frame of the recommendation, it's just that we all eat too much salt, so we just need to cut it back to the recommended dose. And if the whole family does it, I think it's easier also for the child to because of the family and benefit from it.
Dr. Smith: Dr. Alon, I like that idea of it's moving away from that word 'diet,' right? Because I think that has some negative connotation for people and it's really about a lifestyle and healthy nutrition, as you say. Dr. Alon, thank you for the work that you're doing at Children's Mercy, and thank you for coming on the show today. You're listening to Pediatrics in Practice with Children's Mercy Kansas City. For more information, you go to www.ChildrensMercy.org. That's www.ChildrensMercy.org. I'm Dr. Mike Smith, thanks for listening.