SALT LAKE CITY — Fatty liver is found in almost one in five older adolescents, a prevalence not much different from that found in adults, Dr. Jeffrey B. Schwimmer said at the annual meeting of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.
That is a problem, because many of those adolescents also have steatohepatitis, and there are no treatments proven to be of reliable benefit, he said.
It is hard to know how many children have steatosis or steatohepatitis because imaging techniques are not very sensitive. In addition, many patients—even those with steatohepatitis—do not have elevated liver enzymes, which might prompt a biopsy, said Dr. Schwimmer of the department of pediatrics at the University of California, San Diego.
Previous studies estimated the prevalence of fatty liver—which was checked for only in obese children—at anywhere from 10% to 77%, and case series have suggested that from 3% to 10% of children already have cirrhosis when they are biopsied.
So Dr. Schwimmer and his colleagues reviewed the liver slides from autopsies of every child autopsied by the medical examiner in San Diego County from 1993 to 2003. They excluded those children who might be likely to have liver toxicity, such as those with alcohol in their systems, and those who had a condition affecting the liver (Pediatrics 2006;118:1388–93).
In 743 children, most of whom died in accidents or shootings, 13% were found to have a fatty liver. A fatty liver was defined as a liver in which 5% or more of hepatocytes contained a droplet of fat bigger than the cell nucleus. The prevalence ranged from a little less than 1% in children aged 2–4 years up to 17% in those aged 15–19 years. In addition, 82% of the children with fatty liver were male.
Steatohepatitis was found in 23% of the children with fatty liver, or 3% of the total population, a percentage that, translated to the entire population, would suggest that 65 million children in the United States have a fatty liver.
And it was found not only in heavy children, but in 5% of the normal-weight children, compared with 16% of overweight children and 38% of obese children.
It was more common in Hispanic and Asian children (11% and 10%, respectively) than in white children (9%), and was almost nonexistent in black children (1%).
“Blacks seem to be incredibly protected from developing fatty liver disease, regardless of their obesity,” said Dr. Schwimmer.
The benefits of any kind of treatment have not been established, he added.
Three studies have shown that weight loss can improve an elevated ALT level. But close examination of one of those studies shows that the benefit might be limited. In that study, 84 patients with biopsy-proven nonalcoholic fatty liver disease were followed for 1 year, during which they received moderate-intensity weight management (Hepatology 2006;44:458–65).
In all, 77% of those children were overweight or obese at the start, but 35 children lost no significant amount of weight over the year, and only 5 lost weight and had a normalizing of their ALT, Dr. Schwimmer said.
Metformin also seems to be of limited benefit in these patients. Dr. Schwimmer conducted a study of 10 metformin-treated obese adolescents and found that after 24 weeks of treatment only 40% achieved a normal ALT level. Magnetic resonance spectroscopy showed some reduction in liver fat, but those livers did not become “normal,” he said (Aliment. Pharmacol. Ther. 2005;21:871–9).
“I know we all want to do something to help these children; unfortunately there is an awful lot we don't know yet about exactly what that entails,” he said.
A large ongoing study sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases may help provide an answer. That study is looking at either vitamin E or metformin treatment, versus placebo, in pediatric patients, he said.
Blacks seem to be protected from developing fatty liver disease, regardless oftheir obesity. DR. SCHWIMMER