Potassium cuts kidney stones in kids on "K" diet

By David Douglas

NEW YORK (Reuters Health) - Children on the high-fat ketogenic, or "K diet" to control epileptic seizures can prevent the painful kidney stones that the diet can sometimes cause if they take a daily supplement of potassium citrate the day they start the diet, doctors have found.

"We can confidently say this is a safe and powerful way to prevent kidney stones, and it should become part of standard therapy in all ketogenic dieters," senior investigator Dr. Eric Kossoff, from Johns Hopkins Children's Center, Baltimore said in a prepared statement.

"If you wait, it might be too late," he added.

The ketogenic diet is used effectively in many children with epileptic seizures who do not respond to drug therapy. It is believed to work by initiating biochemical changes that eliminate seizure-triggering short circuits in the brain's signaling system.

But the diet, which is made up of high-fat foods with very few carbohydrates, causes a buildup of calcium in the urine and the formation of kidney stones in about 6 percent of those on it.

Potassium citrate taken twice daily, either as powder sprinkled on food or dissolved in water, is believed to inhibit stone formation.

In their study of 301 children treated for epilepsy with the ketogenic diet at Hopkins Children's, Kossoff told Reuters Health, "We found that there was a 7-fold drop in kidney stones on the ketogenic diet...when Polycitra K was used universally at the start of the diet in all patients."

Given the apparent efficacy of potassium citrate, Kossoff said, "We now recommend its use universally for all children on the ketogenic diet."

SOURCE: Pediatrics, August 2009.