Summer bummer: Why kidney stones spike in hot weather

Dr. Saatiah Jaffry [Photo: Denise Ritchie]

It’s summertime in Florida and that could be bad news for your kidneys.

The Mayo Clinic says kidney stones, which affect approximately 3.8 million people in the U.S. each year, are much “more common in the summer.”

Making matters worse, the National Institutes of Health says, “kidney stones are more common in southern parts of the country,” and Florida is about as “southern” as it gets.

So, what exactly are kidney stones and what makes them so seasonal?

Usually they start with dehydration – which is more common in hot weather due to sweat and evaporation.

The International Kidney Stone Foundation in Indianapolis explains. “When the body is dehydrated, the kidneys attempt to conserve water by making urine that is concentrated, and concentrated urine sets up a cascade for crystal formation.”

Certain chemicals – including calcium, oxalates and phosphorous – form crystals that grow into stones and block the flow of urine out of the body. These stones can be incredibly painful and potentially dangerous.

Locally, Dr. Saatiah Jaffry, a board-certified nephrologist with Sebastian River Medical Center and the Sebastian Dialysis Care Center, explains the process.

“Basically, making kidney stones is a matter of chemistry,” says Jaffry. “When the urine becomes super-concentrated, a crystal forms. A uric acid crystal. And then calcium deposits on it and it makes a stone. Eighty percent of kidney stones are calcium stones. Mainly calcium oxalate.”

Jaffry adds that while dehydration and the subsequent concentration of urine may be the root cause of kidney stones, some stones are actually self-inflicted because of what people chose to drink.

For example, “during the summer people might be drinking more soda. Black sodas have high fructose and high sucrose, which can lead to increased formation of kidney stones.”

A lesser known trigger for kidney stones, according to Jaffry, comes from well-intentioned people taking self-prescribed over-the-counter supplements.

“Certain supplements, specifically Vitamin D and Vitamin C, are predisposed to forming kidney stones,” Jaffry says. “I’ve seen this multiple times. I’ll see middle-age people who never had kidney stones [and] … had no family history of kidney stones; then they start taking supplements and, low and behold, they get kidney stones.

“They’ll take Vitamin C supplements,” Jaffry continues, “and then they’ll have a multivitamin with vitamin C in it. They’ll take a magnesium supplement and then they’ll have a multivitamin with magnesium. So they’re taking so many super-therapeutic doses of these minerals that they form stones.”

Calcium supplements, too, bear watching, Jaffry warns. Even those diagnosed with osteoporosis need to be careful about getting too much calcium from supplements during the summer and might want to consider turning to natural sources, such as milk and yogurt, for a couple of months until the temperature goes down.

“I wish people would, before they decide they’re going to start taking 1,500 milligrams of vitamin C a day, first talk to their medical provider,” and not just the clerk behind the counter where supplements are sold.

Moreover, since dietary supplements are not FDA-regulated, it is virtually impossible to know precisely what ingredients are in them, let alone the exact number of milligrams of any vitamin or mineral each tablet or capsule contains.

Taking a “summer vacation” from certain supplements – provided your primary care doctor or specialist agrees – might help you avoid the excruciating pain of kidney stones and could do even more for your long-term health.

People who are prone to kidney stones can suffer irreparable kidney damage which, in turn, can lead to a long-term need for dialysis just to stay alive.

“If people have had a kidney stone,” Jaffry says, “it’s good to get an evaluation. Usually it’s a simple blood test or a urine test. Or maybe a history to see what kind of risk factors you have so that you can make dietary modifications. Sometimes I’ll see people who’ve had stones all their life and every time they get another one it hurts their kidney function.”

Your primary care physician can do that evaluation or refer you to someone who can.

Why is the evaluation so important? Because, aside from the above factors, other medical conditions – such as Crohn’s disease, ulcerative colitis, hyperparathyroidism and genetic disorders – can also make kidney stones more likely to form.

The University of Missouri medical school bluntly states that kidney stones are now nearly twice as common as they were in the early 1990s, so it’s only prudent to seek medical advice now on the best way to avoid them.

Dr. Saatiah Jaffry is board certified in nephrology. She can be reached at her office directly across the street from the Sebastian River Medical Center at 7965 Bay Street where the phone number is 772-918-8487 or at Sebastian Dialysis Care Center at 1807 U.S. 1, where the phone number is 772-581-1041.

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