Many more may need a new liver by their 30s or 40s, say experts warning that pediatricians need to be more vigilant. The condition, which can lead to cirrhosis and liver failure or liver cancer, is being seen in kids in the United States, Europe, Australia and even some developing countries, according to a surge of recent medical studies and doctors interviewed by The Associated Press.
The American Liver Foundation and other experts estimate 2 percent to 5 percent of American children over age 5, nearly all of them obese or overweight, have the condition, called nonalcoholic fatty liver disease.
"It's clearly the most common cause of liver disease," said Dr. Ronald Sokol, head of public policy at the liver foundation and a liver specialist at Children's Hospital and University of Colorado Denver.
Some experts think as many as 10 percent of all children and half of those who are obese may suffer from it, but note that few are given the simple blood test that can signal its presence. A biopsy is the only sure way to diagnose this disease.
As fat builds up, the liver can become inflamed and then scarred over time, leading to cirrhosis, a serious condition, which in years past was mostly caused by hepatitis or drinking too much alcohol. Liver failure or liver cancer can follow, but if cirrhosis has not yet developed, fatty liver disease can be reversed through weight loss.
The disease is most common in overweight children with belly fat and certain warning signs, such as diabetes or cholesterol or heart problems. However, it's been seen in a few children of normal weight.
Genetics, diet and exercise level all play a role. It is most prevalent among Hispanics, relatively rare among African-Americans, and more common among boys than girls.
"There are people in their 30s or early 40s that will require a liver transplant" from developing the condition as a kid, predicts Dr. Jose Derdoy, head of liver transplants at Cardinal Glennon Children's Medical Center in St. Louis. He's treated a 15-year-old, 530-pound boy and many others with the condition.
Experts blame obesity, with about two-thirds of all Americans overweight. With fatty liver disease becoming more common in adults, many experts predict it will become the top cause of liver transplants by 2020.
"There aren't enough livers to go around," says Dr. Philip Rosenthal of the University of California-San Francisco Children's Hospital.
His patient, Irving Shaffino, a 15-year-old Mexican-American who lives outside Lubbock, Texas, was lucky to get a transplant a year ago. He was in end-stage cirrhosis and, at 5-feet-4½, weighed 180 pounds.
Irving had been fat since age 6, thanks to a high-starch, high-fat diet of Mexican food, pizza and burgers, said his mother, Guadelupe Shaffino. At age 8, she said, he had a distended stomach and by his early teens, breathing problems kept him tethered to an oxygen tank at home.
Without health insurance, the family couldn't find a local hospital that would do a transplant.
"My son begged me, 'Don't let me die, Mommy,' so I did everything in my power to find a place to help him. Thanks be to God, we found a way," said Guadelupe Shaffino, a restaurant cook.
UCSF Children's Hospital, with money from a state health program, agreed to do the transplant. Rosenthal, who oversees the hospital's pediatric liver transplant program, took over care of Irving. The doctor said without a new liver Irving would have died, maybe within months.
"He was in bad shape," said Rosenthal.
Soon after tests were completed and Irving got on a transplant waiting list, an organ was found.
"It felt like a miracle, because people say you could be on the transplant list for years," Irving said.
Within a couple of months of the July 26, 2007 operation, Irving had weaned himself from the oxygen tank and could go on walks, although he got winded quickly.
Back home in Texas, his medications are down from 11 to four and Irving said he's replaced soda and fast food with fruit, vegetables and whole grains.
"I want to get into sports again," he said. "I want to get down to maybe 150" pounds.
Sadly, however, Irving has made little progress in losing weight. While he's grown an inch and a half since his operation, he's still obese and his weight was up to 219 last month.
Specialists say many kids diagnosed with fatty liver disease come to subsequent checkups heavier, and at best, just one in four loses significant weight, the only treatment known to stop and even reverse the disease.
"My patients that are successful, the whole family has bought in," increasing exercise and changing diet, said Dr. Stephanie Abrams, a liver and obesity specialist at Texas Children's Hospital. "The problem is that we aren't changing society in favor of becoming lean."
The scope of the disease has only been realized in recent years. Just a handful of cases were reported in medical journals in the 1980s, and in the past, many adult patients were thought to be lying when they denied drinking alcohol.
Only three liver transplants on American children with nonalcoholic fatty liver disease were recorded from 1990 through 2002; two were done last year.
"It really has been only in the last two or three years that this has become more commonplace," said Dr. Ann Scheimann, a pediatric gastroenterologist at Johns Hopkins Children's Center. "It is scary."
Like heart disease, liver disease is silent. Kids may feel fine for years. Any early symptoms, like fatigue and loss of appetite, are vague and usually eclipsed by more conspicuous problems, from diabetes to high blood pressure.
"The majority of children with this still go undiagnosed," said Dr. Jeffrey Schwimmer, head of the Fatty Liver Clinic at Rady Children's Hospital in San Diego. "Some kids have died."
The number of patients at his clinic has roughly tripled over its six years, and he's seen one with cirrhosis just 8 years old.
"Many of these children, their parents have it (fatty liver disease) and don't know it," said Schwimmer.
Experts say the best way to combat the problem is to intervene early, while it can still be reversed, with a medical team working with the whole family, including liver and hormone specialists, a dietitian and counselors.
Last spring, the American Academy of Pediatrics recommended doctors do a blood test of liver enzymes every two years on obese children and overweight ones with high blood pressure or cholesterol or family history of heart disease. A trade group for children's hospitals last year gave similar advice.
Within the last several months, there's been an explosion of research published on it and the role genes may play.
Surprisingly, some research comes from countries not known for high obesity rates: China, India and Iran. More reports come from Australia, England, Greece, Ireland, Israel, Italy and Japan. Doctors say globalization has given even poor countries fast food chains and sedentary pastimes: TV, Internet, video games.
Scientists now are seeking the best ways to treat it.
A small study in Rome showed weight loss helped. The U.S. government is testing the diabetes drug metformin and vitamin E and is funding about 20 other studies, including one that aims to determine how the disease progresses and who is most likely to develop cirrhosis or liver failure.
When her son was diagnosed with advanced liver disease three years ago, Susan Siegfried recalls being "devastated." Curtis, then 12, was just over 5-feet-5 and weighed 179 pounds. About 40 percent of his liver was scarred.
Her husband, Mike, decreed the whole family would change its diet, and all high-fat and junk food was removed from their home in Chester, Ill.
Susan Siegfried said her son went from being the "sit-in-front-of-the-TV, play-video-games kind of kid," tired and sickly, to full of energy and very active. He now bales hay and does other chores on his uncles' nearby farm. Initially, he dropped about 20 pounds. He's shot up 4 inches but only gained 8 pounds in the past two years.
A new liver biopsy last fall showed huge improvement in his liver.
"I'm definitely a lot thinner than I would have been if I hadn't done anything," said Curtis, who found exercising and cutting out sugar and fat wasn't that hard. "If you stick with it, you'll get used to it."