Scott Nellis is barely old enough to get a driver's license but the 16-year-old from Lake City, Minn., has already had something most grown-ups have not -- three episodes of kidney stones.
Once a condition only seen in middle-age adults, kidney stones are showing up in more kids, doctors say, and a handful of pediatric kidney stone clinics have popped up at children's hospitals across the country to help treat these young patients.
Nellis had his first kidney stone when he was 13. He woke up in the middle of the night with a sharp pain on his right side.
"It felt like someone was stabbing me," he said. His parents took him to St. Mary's Hospital in Lake City, where he found out -- much to his surprise -- that he had a kidney stone. He was given a numbing agent for the ache and told to go home, where he eventually passed the stone.
Although kidney stones typically have a strong genetic tendency, Nellis is the first person in his family to have them.
About a year later, he had a second episode. This time, however, he knew exactly what was wrong. But the pain was much worse than before. "I felt like a person was twisting a knife in me," he said.
After Nellis went through the painful ordeal of a second stone, doctors placed him on daily medication and he started to drink more water and watch his diet. He cut back on salt, junk food and caffeinated beverages -- a challenge for any teenager.
Yet despite the preventive measures, Nellis developed a third stone at age 15.
Many parents react with surprise upon learning their child has kidney stones.
"They say they've never heard of a kid having a kidney stone, so they think it must be something bad," said Dr. John Pope, an associate professor of urologic surgery and pediatrics at the Monroe Carrell Jr. Children's Hospital at Vanderbilt in Nashville, Tenn.
According to Pope, who has recently compiled statistics from his clinic, in the last couple of years his clinic has seen more than 100 young adults with kidney stones, compared to about 20 such patients 10 years ago. Although there are no nationwide statistics kept, he says his gut feeling is that there is an increased incidence of kidney stones in children.
What's concerning about this is that often it is a lifelong predisposition, pointed out Dr. Dawn Milliner, who is Nellis' doctor and a professor of pediatrics and internal medicine in the division of nephrology at the Mayo Clinic in Rochester, Minn.
"It's not something that usually happens once or never again," Milliner said. "The likelihood of having another stone is high."
Some environmental exposures can also lead to kidney stones in children. Recently, milk products in China that were tainted with the industrial chemical melamine were linked to an increase in the development of kidney stones in babies and children there.
"The problem is the melamine, which was directly toxic to the kidneys and was crystallizing out in the urine to form stones," Nelson said.
"As far as we know, this is an isolated problem and is not an issue here," Milliner said.