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Preventing Kidney Stones Through Better Nutrition

Kidney stones are material that forms from substances in the urine. Many kidney stones pass out of the body without help from a doctor, however, there are times when a stone will not go away. This is when your physician might recommend medical intervention to dissolve the stone.

In this podcast, Yu-Kuan Lin, MD, discusses kidney stones and how your diet can make a big difference in the formation of stones.
Preventing Kidney Stones Through Better Nutrition
Yu-Kuan Lin, MD
Dr. Yu-Kuan Lin earned his Bachelor of Arts degree in both Biology and Psychology in 2006 from the University of Virginia and in 2011 completed medical school at Pennsylvania State University College of Medicine. He completed his residency program at Pennsylvania State Milton S. Hershey Medical Center in 2016. Dr. Lin specializes in General Urology, BPH, Kidney Stones, Robotic Surgery, Bladder Cancer, Kidney Cancer, and Prostate Cancer.

Learn more about Dr. Yu-Kuan Lin

Melanie Cole (Host): You’ve probably heard the term kidney stones. But do you even know what they are or how they form? My guest today is Dr. Yu-Kuan Lin. He’s a urologist at St. Luke’s Cornwall Hospital. Well to the show Dr. Lin. So, what are kidney stones?

Dr. Yu-Kuan Lin, MD (Guest): So, kidney stones are these deposits of mineral and salt that are formed in the kidneys. They can be caused by many different reasons. Essentially, it becomes a solid material that forms in the kidney and sometimes patients can have stones that are not symptomatic and sometimes patients can have stones that are symptomatic. And they typically come and see us when they have an acute episode from a kidney stone attack.

Melanie: How do they form? I mean is there something we are doing that cause them to form or are certain people more at risk?

Dr. Lin: Absolutely. I generally tell my patients that there are four reasons why patients can form kidney stones. The most common cause of kidney stones in the United States is secondary to dehydration. The way I think about that etiology is a chemistry problem. If you consume more fluid it tends to dilute your urine more and therefore the chemicals or these salts that your kidneys produce won’t have enough concentration for them to form stones. The second reason actually has to do with the amount of salt that we intake in our daily diet. Increasing salt intake more than two grams a day can also be a risk factor for kidney stone formation. In general, there is more than ten different types of kidney stones that a patient can produce; each of them come with their own risk factors and depending on the kind of kidney stones you make, there are specific dietary factors that we can try to do to minimize your risk. And that’s the third reason for forming kidney stones which is associated with your dietary intake.

But in general, to decrease the number of kidney stones from a diet in addition to drinking lots of fluid, also decreasing the amount of salt is to actually have balanced and healthy meals. Similar to what a cardiologist will recommend to a patient, it is something that can also be helpful for decreasing kidney stone formation. And the fourth reason has to do a little bit with genetics. I mean both that in the sense of if you have a family history of kidney stones or sometimes your genes will make your kidneys at a higher risk of producing these stones, then these patients are the ones that we usually do a little bit more a workup study and therefore find the reasons for them to have these stones and put them on medication.

Melanie: So, we will talk a little bit more about how diet affects the formation of kidney stones in just a bit, but are there certain times of the year when you see more of these than others?

Dr. Lin: Oh absolutely. So, kidney stones tend to form during the warmer time of the year so in general, that’s usually the summer months and typically they form again secondary to the issue with the dehydration. It’s not just how much you drink in but during these warmer months, you also have to realize that you tend to sweat a little bit more and therefore get a little bit more dehydrated. So, summer months are a risk factor for developing these stones. And then depending on where the stone and when it decides to come down and cause issues, that’s when you may develop symptoms from the stones. So, the time you make the stone and the time you develop symptoms can be at different times of the year. In addition to having the summer months having stones, there is also a phenomena called the stone belt and that’s usually involving most of the times the southern part of the United States but in our northeast region, the Pennsylvania, New Jersey and also parts of New York, we are also at a higher risk of developing these stones and a lot of patients- a lot of researchers believe that this is also secondary to the weather phenomenon.

Melanie: So, what are some of the symptoms that someone might experience if that stone is causing trouble?

Dr. Lin: So, interestingly, stones can cause a variety of symptoms. And sometimes patients can have stones in the kidneys and they may not have any symptoms meaning no pain, no burning, no blood in their urine, no issues like that. Usually the start causing symptoms if it decides to travel from the kidney down towards the bladder. It has to travel through this tubing called a ureter. The majority of the symptoms associated with kidney stones is when the stone causes a blockage of this ureter and the symptoms can range from blood in the urine, flank pain, nausea, vomiting and sometimes the pain can travel from the flank area towards the groin area depending on what the path of that stone is.

Melanie: Dr. Lin, everyone has heard about passing stones, passing kidney stones and men in particular find this to be quite frightening. What is the treatment, and do they generally pass on their own and how does that happen?

Dr. Lin: Correct, in general, the rule of thumb is smaller stones have a higher chance of passing versus larger sized stones. But every patient is different, and everyone has a different experience at passing stones. The majority of patients if they are able to tolerate the pain, the other symptoms associated with stone passage, such as nausea and vomiting, we typically have them give a chance to pass this stone on their own. Certainly, we do prescribe pain medicine, medicine to help with the other symptoms of nausea and also a medicine to open up the tubing, the ureter so the stone can pass easier. I would say the majority of the patients actually pass stones on their own. It does take a time, a couple of weeks sometimes but the majority of them can pass stones on their own. If you are not able to pass the stone or if you have other worsening symptoms such as poor pain control, worsening nausea and vomiting and you are not able to keep yourself hydrated, we have many different options and procedures to remove the stone for you.

Melanie: So, you said it could take up to a couple of weeks to pass a stone. Is this during those couple of weeks, can the person go about their daily life or is this something they’re kind of in pain and staying at home and feeling sick?

Dr. Lin: It varies a little bit. The way that the stone causes pain as I mentioned before is if it causes blockage of the urine flow from the kidney down to the bladder. When the stone travels down this tubing, if it is oriented and, in a situation, where the urine is able to flow past the stone, patients are actually not having much symptoms. So, you could actually go about your daily life without any problems. And it is only when the stone either goes into a location where it starts slowing down the flow of urine that’s when you can get symptoms. So, most of the patients have what we call intermittent renal colic which is that you have symptoms once in a while. It’s hard to define what that once in a while is because everyone is different. But it’s unusual for patients to be in constant pain for the two weeks when they are passing the stone. It is usually more of intermittent in nature.

Melanie: So, we mentioned diet earlier. How can diet help us prevent stones from forming and you mentioned something that a cardiologist might recommend a good Mediterranean, good heart healthy diet. What else can help keep us from forming these stones?

Dr. Lin: So, if we have to go with dietary recommendations, the most common reason as I mentioned before for the kidney stone formation is due to dehydration and that’s across all forms of kidney stones. Again, make sure that you need to drink enough to keep your urine diluted and usually the recommendation is at least 64 ounces of fluid a day or enough to produce about 2.5 liters of urine a day. And that’s part of the diet, making sure that you are staying hydrated either by keeping a bottle of water with you at all times or making sure that with meals you consume fluids and diet.

The other issue has to do a little bit more in terms of the specific kinds of stones that you make. For example, the most common kind of kidney stones that Americans make are called calcium oxalate stones. Now these stones are two parts to it. One part has a calcium part and the other part is the oxalate part. And it is a common misconception that oh I form calcium stone, therefore I need to stay away from calcium. That’s actually not true. You need to make sure that you have a steady supply of calcium in your diet to actually prevent calcium stone formation and the reason for that is if you happen to deprive yourself of calcium, your body is going to get it from your bones naturally and that itself can predispose you to developing kidney stones. So, it is actually, you want to make sure that you don’t have a calcium depleted diet to avoid making these calcium oxalate stones.

But more of the other part in terms of the oxalate, we actually recommend patients who make these calcium oxalate stones to follow what’s called an oxalate diet. And this is something that you can do a lot of research online. There a lot of lists that talk about foods and the amount of oxalate that they have. In general, things that have high oxalate could be things like berries, unfortunately kale and spinach which are healthy for you in the heart standpoint have a high amount of oxalate in them and if patients realize that they are consuming these foods in excess, decreasing the consumption can often decrease the amount of oxalate their body can absorb and therefore decrease the amount of oxalate their kidney’s excrete and therefore decrease the amount of calcium oxalate stones that they make.

Melanie: So, really first of all, because you answered one of my questions before I even asked it. I was thinking when you said about calcium, so does that mean we should restrict it and you said absolutely not. And people look to calcium in their diet from certain foods, but then you mentioned kale. I don’t know how many people overeat it, but if this is something that is so healthy for us, what do you want people to know about amounts that are kind of acceptable and how would we know what kind of stones that we form?

Dr. Lin: So, a key thing for all patients who have kidney stones is try to either catch the stone if they pass it. if we are able to do that, we can analyze the stone that you make and based on the composition, we can give a little bit more specific dietary recommendation. If you form for example uric acid stones, which are the second kind of most common kind of stones that we see in our office; having a low oxalate diet actually doesn’t help because the pathophysiology of that is completely different. So, the main thing is try to see if you can catch your stone or have your – to catch your stone so we can analyze it. Second thing is to perform what’s called a metabolic workup and what that involves is a little bit more of labor intensive process where we have patients collect urine for 24 hours. That allows us to analyze the amount of crystals, these elements that your kidneys secrete so we can identify what is oversecreted. And if we can identify things that are oversecreted, we can either use more of a specific dietary recommendation to decrease that value or we can use medications to decrease that value.

Melanie: So interesting. What great information. Dr. Lin, wrap it up for us with your best advice, what you tell people every day about kidney stones when they ask you?

Dr. Lin: So, I tell patients that kidney stones unfortunately is a very common issue that a lot of Americans experience with our daily activities, the amount of hydration we have and overall diet; it’s becoming more of a prevalent situation that patients have to experience. I will recommend that patients who have a family history of kidney stones or a personal history of kidney stones see their primary care doctor just to get some screening to make sure that you don’t have any issues that we need to address, but regardless of what the situation with kidney stones, we have a lot of options to help prevent stones and also to help treat stones in case you are having an acute attack.

Melanie: Thank you so much. What an interesting topic. This is Doc Talk presented by St. Luke’s Cornwall Hospital. For more information, please visit that’s I’m Melanie Cole. Thanks so much for listening.