A Rise in Kidney Stones Is Seen in U.S. Children ... NY Times October 28, 2008

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http://www.nytimes.com/2008/10/28/health/28kidn.html A Rise in Kidney

Stones Is Seen in U.S. Children By

LAURIE TARKAN NY

Times October 28, 2008 To the great surprise

of parents, kidney stones, once

considered a disorder of middle age, are now showing up in children as young as

5 or 6. While there are 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 older

doctors would say in the ’70s and ’80s, they’d see a kid with

a stone once every few months,” said Dr. Caleb P. , a urology

instructor at Harvard Medical School who is co-director of the new kidney stone

center at Children’s Hospital Boston. “Now we see kids once a week

or less.” Dr. C. Pope IV,

an associate professor of urologic surgery and pediatrics at the Monroe Carell

Jr. Children’s Hospital at Vanderbilt in

Nashville , said, “When we tell parents,

most say they’ve never heard of a kid with a kidney stone and think

something is terribly wrong with their child.” In

China recently,

many children who drank milk tainted with melamine — a toxic chemical illegally added to

watered-down milk to inflate the protein count — developed kidney stones. The increase in the

United States is attributed to a host of factors, including a food additive that is both

legal and ubiquitous: salt. Though most of the research

on kidney stones comes from adult studies, experts believe it can be applied to

children. Those 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.) And

the two biggest risk factors for this binding process are not drinking enough

fluids and eating too much salt; both increase the amount of calcium and

oxalate in the urine. Excess salt has to be

excreted through the kidneys, but salt binds to calcium on its way out,

creating a greater concentration of calcium in the urine and the kidneys. “What

we’ve really seen is an increase in the salt load in children’s diet,” said Dr.

Bruce L. Slaughenhoupt, co-director of pediatric urology and of the pediatric

kidney stone clinic at the University of Wisconsin. He and other

experts mentioned not just salty chips and French fries, but also processed

foods like sandwich meats; canned soups; packaged meals; and even sports drinks

like Gatorade, which are so popular among schoolchildren they are now sold in

child-friendly juice boxes. Children also tend not

to drink enough water. “They don’t want to go to the bathroom at

school; they don’t have time, so they drink less,” said Dr.

Neu, medical director of pediatric nephrology and the pediatric stone clinic at

s Hopkins Children’s Center in Baltimore. Instead, they are likely to

drink only once they’re thirsty — but that may be too little, too

late, especially for children who play sports or are just active. “Drinking more

water is the most important step in the prevention of kidney stones,” Dr.

Neu said. 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. “It’s no

longer a middle-aged disease,” Dr. said. “Most of us suspect

what we’re seeing in children is the spillover of the overall increase in

the whole population.” The median age of

children with stones is about 10. Many experts say the

rise in obesity is contributing to kidney stones

in children as well as adults. But not all stone centers are seeing overweight

children, and having a healthy weight does not preclude kidney stones.

“Of the school-age and adolescent kids we’ve seen, most of them

appear to be reasonably fit, active kids,” Dr. said.

“We’re not seeing a parade of overweight Nintendo players.” Dr. Slaughenhoupt has

seen more overweight children at his clinic. “We haven’t compared

our data yet,” he said, “but my sense is that children with stones

are bigger, and some of them are morbidly obese.” Dr. Pope, in

Nashville , agreed. His

hospital lies in the so-called stone belt, a swath of Southern states with a

higher incidence of kidney stones, and he said doctors there saw two to three

new pediatric cases a week. “There’s

no question in my mind that it is largely dietary and directly related to the

childhood obesity epidemic,” he said. Fifty to 60 percent of

children with kidney stones have a family history of the disease. “If you

have a family history, it’s important to recognize your kids are at risk

at some point in their life,” Dr. said. “That means

instilling lifelong habits of good hydration, balanced diet, and

avoiding processed high-salt, high-fat foods.” There is also evidence

that sucrose, found in sodas, can also increase risk of stones, as can

high-protein weight-loss diets, which are growing in popularity among

teenagers. A common misconception

is that people with kidney stones should avoid calcium. In fact, dairy products

have been shown to reduce the risk of stones, because the dietary calcium binds

with oxalate before it is absorbed by the body, preventing it from getting into

the kidneys. 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. One Saturday last

February, 11-year-old Tessa Cesario of Frederick ,

Md. , began having back pains. An

aspiring ballerina who dances en pointe five nights a week, she was used to

occasional aches and strains. But this one was so intense that her parents took

her to the doctor. The pediatrician

ordered an X-ray, and when he

phoned with the results, her parents were astonished. “I was afraid he

was calling to say she pulled something and wouldn’t be able to

dance,” said her mother, Theresa Cesario. Instead, they were told that

Tessa had a kidney stone. “I thought older

men get kidney stones, not kids,” Ms. Cesario said. The treatment for

kidney stones is similar in children and adults. Doctors try to let the stone

pass, but if it is too large, if it blocks the flow of urine or if there is a

sign of infection, it is removed through one of two types of minimally invasive

surgery. Shock-wave lithotripsy

is a noninvasive procedure that uses high-energy sound waves to blast the stones

into fragments that are then more easily passed. In ureteroscopy, an endoscope

is inserted through the ureter to retrieve or obliterate the stone. Tessa Cesario is

taking a wait-and-see approach. Her stone is not budging, so her parents are

putting off surgery until they can work it into her dance schedule. In the

meantime, she has vastly reduced her salt intake by cutting back on sandwich

meats, processed soups and chips. And, her mother said,

“she drinks a ton more water.”