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.
More Cases at Earlier Ages
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."
Kidney Stones Can Remain a Mystery
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.
Fortunately, Milliner noted, two-thirds to three-quarters of the time physicians can pinpoint the cause or predisposing factors that can minimize or reduce the odds of recurrence in children and teens.
There are some cases, though, where the cause of kidney stones remains a mystery. Just ask Kate Mercier, who was first diagnosed with them at age 8 and has been through at least 12 operations related to her stones.
The 17-year-old high school senior in a suburb south of Boston still might not know exactly why she's so prone to forming kidney stones, but all the X-rays, CT scans and ultrasounds she's been through in her young life have helped her choose a career path. She's off to college next year to study radiology, where she might have an edge on her classmates because of her firsthand familiarity with the procedures -- and plenty of compassion for the patients.
Although Mercier's been through a lot of surgeries for her kidney stones, she said, "I've never had pain. I have twinges from time to time, but they almost feel like muscle contractions."
In her case, there is a family history: Both her father and her aunt have had kidney stones. But each of them had only one stone, whereas Mercier tends to form clusters of them. And while she said, "I'll probably have them my whole life," she hasn't let them stop her from doing things -- including earning a brown belt in karate.
It's Not Only in Adults Anymore
Dr. Caleb Nelson, a urologist and co-director of the pediatric kidney stone clinic at Children's Hospital in Boston, said he also thinks the number of children with kidney stones is growing -- though he said the reasons for this are not entirely known.
"It's not simply that we're finding more of them because imaging is picking them up," he said. "We're seeing more kids come in with stone-related symptoms."
Physicians believe, however, that the two main contributors appear to be poor fluid intake and too much dietary salt -- mainly from processed, canned, boxed and junk foods.
Tiny Stones May Cause Enormous Pain
The most common symptom of a kidney stone in a child is blood in the urine, said Dr. Bruce Slaughenhoupt, co-director of pediatric urology and the pediatric kidney stone clinic at the University of Wisconsin in Madison. "This is a more common complaint than pain, perhaps because younger kids might have difficulty expressing their pain."
A younger child is also more apt to say they have a tummy ache, likely with nausea and vomiting, while older children can verbalize if their pain is in the lower back or on their side.
Surprisingly, the size of a kidney stone makes no difference to pain levels, explained Slaughenhoupt. "The pain occurs when the stone gets stuck and blocks the ureters. This blockage creates pressure, and pressure is what causes pain."
While kidney stones are nearly painless for some people, Milliner said, others describe it as the worst pain they have ever felt.
"I know some women who have gone through childbirth and also passed a kidney stone, and they say passing the stone was much worse," Nelson said.
Fortunately, most people can take steps to avoid kidney stone formation. Pope tells his patients that a good rule of thumb is to drink half your body weight in ounces of water per day. And he also tells them to check the color of their urine for an indication as to whether they're getting enough liquids. If the urine is dark yellow or brownish in color, then it's too concentrated.
"The key is to keep urine diluted," Pope said.