By Gregory Carter, MD
Kidney stones can be one of the most painful and debilitating conditions people ever have to deal with. Unfortunately, they are fairly common. It is estimated that 10-12 percent of men and 7 percent of women are affected by kidney stone disease.
Kidney stones are becoming more and more common in both men and women, with the incidences having nearly doubled in the past 25 years. Stone disease is more prevalent in some families and can be passed down genetically to successive generations. Kidney stone disease can be related to diet, fluid intake, weight or underlying medical problems. There is an array of minimally invasive, or even noninvasive, treatment techniques and technologies available today that can be employed to destroy or remove kidney stones. However, our primary goal should be preventing them in the first place.
Many patients simply do not consume enough liquids or fluids on a daily basis. This results in what is called concentrated urine, which increases the likelihood that stone-forming minerals and proteins will come into contact and stick together, growing into crystals, and then stones. By consuming adequate fluids and reducing the concentration of the urine, these minerals and proteins stay dissolved in the water of the urine, and do not “gang up” to form stones.
Normal adults do best with 50-60 ounces of total fluid intake per day. Those with a tendency to form stones should aim for 70-80 ounces per day. These amounts need to be increased if a patient is perspiring due to work or recreation, or if there are other causes for fluid loss, such as diarrhea or vomiting. You can get a pretty good idea how you are doing with your efforts at hydration by just looking at the color of your urine. Concentrated urine is darker yellow or even orange in color, while diluted urine, which keeps minerals and proteins dissolved, is very pale or even clear in color.
Limit salt intake
Consumption of salt results in the kidney needing to eliminate excess sodium from the blood. It turns out that the sodium “drags” calcium with it, resulting in increased amounts of calcium in the urine, which may not stay dissolved, resulting in stone formation. Limiting salt intake will reduce the amount of calcium and the risk of stone formation. This can be accomplished in most patients without counting the sodium content of everything they eat. It is usually sufficient to simply avoid salting your food while cooking or at the table, and minimize salty snacks.
What is citrate?
In some cases, patients suffering from kidney stones will be advised to regularly consume a beverage that contains citrate, a natural stone inhibitor. Citrate is a natural substance derived from body metabolism and dietary intake, and acts as a natural stone inhibitor in the urine. Citrate is found in abundance in lemonade, as well as lemon-flavored Crystal Lite. Including a couple of glasses of one of these beverages as part of your daily fluid intake can increase the citrate level in your urine and decrease the likelihood of stone formation.
What about milk?
It turns out that older recommendations to avoid dairy, or other calcium containing foods or beverages, no longer apply to most patients with stone disease. In fact, increased dietary calcium can actually decrease stone formation by binding another substance, known as oxalate, carrying it out in the stool, and preventing its absorption into the bloodstream, where it is ultimately filtered out of the blood and ends up in the urine. The level of oxalate in the urine is actually ten times more important in the formation of kidney stones than calcium. Using dietary calcium to remove dietary oxalate makes sense for stone prevention.
The role of weight
Obesity is a major risk factor for stone disease. The overall increase in the incidence of stones, particularly in women, over the past 25 years is thought to be due to the increasing prevalence of obesity in our society. Here is yet another reason to watch your waistline.
Gregory Carter, MD, is a urologist with Pisgah Urology. (828) 883-5858
Mission Health’s urologists provide comprehensive care for kidney stones, focusing on prevention, while also providing the latest techniques and technology for the treatment of painful, problematic stones.