TRENTON, N.J. — In a new and disturbing twist on the obesity epidemic, some overweight teenagers have severe liver damage caused by too much body fat, and a handful have needed liver transplants.
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 children in the United States, Europe, Australia and even some developing countries, according to recent medical studies and doctors.
About 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, the American Liver Foundation and other experts estimate.
"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 the University of Colorado at 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 the disease. Like heart disease, liver disease is silent; kids may feel fine for years.
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 all play a role. It is most prevalent among Hispanics, relatively rare among African-Americans, and more common among boys than girls.
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.