STEAMBOAT SPRINGS, COLO. – Kidney stones, historically considered an adult malady, have become vastly more common among children during the past decade, in concert with the obesity epidemic.

Moreover, the clinical presentation of urolithiasis in children is often different than it is in adults. As a result, physicians are frequently caught off guard.

Dr. Beth A. Vogt

"The diagnosis of kidney stones is often not the first thing on the differential diagnosis list – or even on the list – for a child with abdominal pain," Dr. Beth A. Vogt observed at a meeting on practical pediatrics sponsored by the American Academy of Pediatrics.

The younger the child with a kidney stone, the more likely the clinical presentation will be nonspecific abdominal pain rather than the flank pain or renal colic typical in affected adults, according to Dr. Vogt, a pediatric nephrologist at Case Western Reserve University, Cleveland.

Thus, in the child with nonspecific abdominal pain, it’s important to add urolithiasis to the differential diagnosis list, which classically has included viral gastroenteritis, appendicitis, cholecystitis, intussusception, and food poisoning, she said.

Gross hematuria is present in 30%-40% of children who present with kidney stones. Dysuria is also common. In addition, asymptomatic kidney stones are frequently detected incidentally in children undergoing ultrasound or CT following traumatic injury.

The primary care physician’s role in pediatric urolithiasis is to make the diagnosis, begin acute management with hydration and pain control, hospitalize if necessary, and refer the patient to urology for intervention if the stone is so large it’s unlikely to pass.

Also, referral to a nephrologist is recommended after a first-ever stone has passed and the child has resumed normal activities. The nephrologist’s job is to figure out why the child is forming stones and to come up with a specific prevention plan (for example, a low-sodium diet in patients with hypercalciuria, or antibiotics in children with infection-related struvite stones), Dr. Vogt continued.

"In adults, the standard practice is to wait until they prove to be recurrent stone formers before doing a work-up. That’s not the case in children. Don’t wait until after a child has had several stones to refer to nephrology. We find something metabolically wrong in about 75% of the kids," she said.

The diagnosis of pediatric urolithiasis is suggested by the combination of abdominal or flank pain, hematuria on a urine dipstick test, and crystals in the urine upon microscopic examination. A couple of caveats, though: Recent studies indicate that up to 15% of kids with active stone disease have a negative urinalysis, so urolithiasis can’t be ruled out on the basis of a negative urine dipstick. Also, many children who don’t have kidney stone disease have crystals in their urine.

The best initial diagnostic imaging study is kidney ultrasound. It doesn’t involve radiation, which is an important advantage because some young patients will continue making stones and will therefore need to undergo imaging many times.

02/03/12  

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EXPERT ANALYSIS FROM A MEETING ON PRACTICAL PEDIATRICS SPONSORED BY THE AMERICAN ACADEMY OF PEDIATRICS

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