Major Finding: Nonalcoholic fatty liver disease in obese children, adolescents, and young adults was twice as high among males as females, with 27% vs. 13% having ALT levels above 40 IU/L. The NAFLD prevalence increased with age in males but decreased with age in females.
Data Source: A prospective, cross-sectional study of 156 obese youth aged 5-20 years.
Disclosures: Dr. Gupta stated that he had no conflicts of interest.
BOSTON — Nonalcoholic fatty liver disease was found in nearly 1 in 5 of 156 obese children and young adults aged 5-20 years in a cross-sectional analysis.
In the study—the first to assess the prevalence of nonalcoholic fatty liver disease (NAFLD) in obese children by sex and age—more than half of the males aged 16-20 years had NAFLD. “Obesity in children is not a cosmetic disease. There are real complications,” Dr. Rishi Gupta reported at the meeting.
The findings suggest that liver function testing should be considered in obese children with dyslipidemia and/or insulin resistance, said Dr. Gupta, a pediatric endocrinology fellow at the State University of New York Downstate Medical Center, Brooklyn.
The multiethnic group of 86 females and 70 males all had body mass indexes (BMIs) greater than the 95th percentile, but did not have diabetes, abnormal thyroid function, or liver disease due to hepatitis or Wilson's disease. A total of 30 (19%) had levels of alanine aminotransferase (ALT) greater than 40 IU/L, generally considered the cutoff to indicate NAFLD. More recently, cutoffs of greater than 30 IU/L for males and 19 IU/L for females are now being used in Europe and in some U.S. labs.
The subjects with elevated ALT did not differ from those with ALT levels at or below 40 IU/L in age (average, 12 years) or BMI (34 kg/m
The prevalence of NAFLD was twice as high in the males as the females, with 27% vs. 13% having ALT levels above 40 IU/L. Males with NAFLD had significantly higher triglycerides than did females with NAFLD (231 vs. 193 mg/dL), and also had lower HDL cholesterol (34 vs. 35 mg/dL). Males and females with NAFLD did not differ significantly with respect to age, BMI, or HOMA-IR.
The prevalence of NAFLD rose with age, from 14.5% for 5- to 10-year-olds to 18% for 11- to 15-year-olds, to 31% for 16- to 20-year-olds. However, when broken down by sex, the prevalence of NAFLD actually dropped with age in the females, from 15.1% in the youngest group to 14.7% in the 11- to 15-year group to 7.1% in the older teens/young adults. In contrast, among males the NAFLD, prevalence rose with age from 13.6% to 24.2% to 53%.
Over half of obese males aged 16-20 years had NAFLD, said Dr. Rishi Gupta.
Source ©Jean Whiteside Photography
Labs Incorrectly ID ALT Thresholds
The findings by Dr. Gupta and associates are consistent with the existing literature and society guidelines created because of the high rates of NAFLD in overweight and obese children.
The Study of Child and Adolescent Liver Epidemiology was a large autopsy series in a community-wide setting. Based upon liver histology, this study estimated the prevalence of NAFLD at 9.6% in children aged 2-19 years. Moreover, it was demonstrated that fatty liver prevalence increases with age, is higher in boys than girls, and is high in Hispanics and low in African Americans (Pediatrics 2006;118;1388-93).
Three years ago, an expert committee assembled by the Centers for Disease Control and Prevention, the American Medical Association, and 15 health organizations released recommendations on the Assessment, Prevention, and Treatment of Child and Adolescent Overweight and Obesity. Within those guidelines are recommendations that children aged 10 years and older should receive biannual screening for NAFLD if they have a BMI at the 95th percentile or greater (obese) or a BMI between the 85th and 94th percentiles (overweight) and other risk factors. Furthermore, the committee recommended that an ALT or aspartate transaminase (AST) result twice that of normal levels should prompt a consultation with a pediatric hepatologist (Pediatrics 2007;120:S164-92).
Two years ago, the Lawson Wilkins Pediatric Endocrine Society and the Endocrinology Society published guidelines suggesting that obese children, regardless of age, be screened for NAFLD (J. Clin. Endocrinol. Metab. 2008;93:4576-99).
Last month, a new publication from our group showed that ALT is incorrectly interpreted in many children's hospitals throughout the United States. Imagine that a primary care physician keeps up with the latest guidelines and correctly screens a child for liver disease but never knows that the child has liver disease because the electronic medical system does not flag the results with an “H,” because the laboratory is using the incorrect threshold for detection. The newly derived thresholds for ALT in boys and girls, if applied, will greatly improve the rate of detecting NAFLD (Gastroenterology 2010;138:1357-64).