A Rise in Kidney Stones Seen in U.S. Children
While there is no reliable data on the number of cases, pediatric urologists and nephrologists across the country say they are seeing a steep rise in young patients. Some hospitals have opened pediatric kidney stone clinics.
The increase in the United States is attributed to a host of factors, including high levels of sodium. Studies have found that dietary factors are the leading cause of kidney stones, which are crystallizations of several substances in the urine. Stones form when these substances become too concentrated. Forty to 65 percent of kidney stones are formed when oxalate, a byproduct of certain foods, binds to calcium in the urine. (Other common types include calcium phosphate stones and uric acid stones.)
The two biggest risk factors for this binding process are lack of fluid intake and increased dietary sodium; both increase the amount of calcium and oxalate in the urine. Excess salt is excreted through the kidneys, binding to calcium and thus creating a greater concentration of calcium in the urine and kidneys.
The incidence of kidney stones in adults has also been rising, especially in women, and experts say they see more adults in their 20s and 30s with stones; in the past, it was more common in adults in their 40s and 50s. The median age of children with stones is about 10.

Children with kidney stones can experience severe pain in their side or stomach when a stone is passing through the narrow ureter through which urine travels from the kidneys to the bladder. Younger children may have a more vague pain or stomachache, making the condition harder to diagnose. Children may feel sick to their stomach, and often there is blood in the urine.

Source: Laurie Tarkan, New York Times Health: October 27, 2009