Why the Risk of Kidney Stones Increases in the Summer

Kidney Stone Pain

Summer offers the fun of barbecues, swimming and other outdoor activities. The warmer months also mean an increased risk for kidney stones.

About one of 11 people in the United States has kidney stones, and they’re nearly twice as common now as in the early 1990s, according to the National Institutes of Health.

Of those suffering from the painful condition, more patients go to the doctor during the summer than any other time of the year, said Kunal Malhotra, MD, a kidney specialist at MU Health Care.

“In the summertime, people lose a lot of fluid through sweat and get dehydrated, because of the hot weather,” Malhotra said. “If this fluid loss is not replaced by drinking extra water, the kidneys will make concentrated urine to conserve body water and this concentrated urine is a perfect condition for formation of stones.” 

Dr. Malhotra
Dr. Kunal Malhotra

Kidney stones form when the normal balance of water, salts and minerals in urine changes. When that balance is disrupted — through a loss of fluid, for instance — substances that normally pass out of the body through urine separate and form stones, which can be as small as a grain of sugar or as big as a golf ball.

Malhotra’s first recommendation to prevent stones is to drink water.

“People who are prone to kidney stones should drink enough water to make about 2½ liters of urine a day,” he said.

People susceptible to one of the most common kidney stones — calcium oxalate — should limit foods high in oxalate, which include nuts, bran, spinach and chocolate among other foods. Excess oxalate is the culprit in causing this type of stone to form.

Malhotra said people often believe it’s calcium causing the problem, so they cut back on milk and other calcium-rich drinks and food, but he said that’s a misconception that can actually lead to more calcium oxalate stones.

When people drink milk or eat dairy, the calcium in that dairy combines with oxalate in food and it passes through the body unabsorbed. When people reduce or stop the calcium intake, the oxalate in the diet gets absorbed into the body and then goes into the urine and forms stones.

Uric acid stones are another common kidney stone. They can form when people don’t drink enough fluids, lose too much fluid or eat a lot of foods high in animal protein. In those people, it’s important to limit animal protein and also sugary sodas because they’re high in fructose corn syrup, which promotes uric acid synthesis. People who suffer from diabetes and obesity are particularly at higher risk of developing uric acid stones.

For people who don’t like plain water, Malhotra said it’s OK to add Crystal Light drink mix or a lemon wedge.

“The cheapest advice I can give is to squeeze a lemon in the water and drink that,” Malhotra said, “because lemon has natural occurring citrate and that can help prevent a kidney stone.”

When it comes to kidney stones, prevention is truly the key. Through simple urine tests, doctors can give more specific dietary recommendation to people who have tendency to form kidney stones.

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