NEW ORLEANS — Serum alanine aminotransferase, a noninvasive marker commonly used to assess nonalcoholic fatty liver and related liver dysfunction, appears to be useful in identifying children with metabolic syndrome and its components.
“Elevations of alanine aminotransferase within normal range relate strongly to metabolic syndrome and its components and may help improve the risk assessment of this condition in the pediatric population,” Dr. Dharmendrakumar Patel said at the Southern regional meeting of the American Federation for Medical Research.
Dr. Patel and colleagues from the Tulane (University) Center for Cardiovascular Health in New Orleans reported data from 1,524 children aged 4–11 years (62% white, 51% male) and 1,060 adolescents aged 12–18 years (58% white, 51% male) examined as part of the Bogalusa Heart Study.
Serum alanine aminotransferase (ALT) and cardiovascular risk factors were measured at baseline. The acceptable cutoff points for the metabolic variables aren't established for children, so adverse levels were defined as values above the age-, race-, and gender-specific 75th percentiles of body mass index (BMI), systolic blood pressure, ratio of total cholesterol to HDL cholesterol, and homeostatis model assessment: insulin resistance (HOMA-IR). A clustering of adverse levels of all four variables denoted metabolic syndrome. Age-, race-, and gender-specific quartiles of ALT were used for analysis.
Overall, 25% of children and 29% of adolescents in the top quartile of ALT had adverse levels of three or four metabolic syndrome risk factors. This clustering was significantly higher than expected, Dr. Patel said.
When the researchers used an area under the receiver operating curve, the diagnostic accuracy of ALT to classify pediatric patients with metabolic syndrome was 67% in children and 82% in adolescents.
ALT levels were significantly higher in white children, compared with black children and in male adolescents, compared with female adolescents, said Dr. Patel, a research analyst and field epidemiologist at the center.
In children, the average ALT level was 17 U/L in both white boys and girls, compared with 16 U/L in black boys and 15.3 U/L in black girls.
In adolescents, the average ALT level was 19 U/L in both white and black boys, compared with 16 U/L in white girls and 14.6 U/L in black girls.
Children and adolescents with ALT levels in the top quartiles, compared with the bottom quartiles, had an increased prevalence of adverse levels of body mass index, systolic blood pressure, ratio of total cholesterol to HDL cholesterol, and HOMA-IR index, as well as metabolic syndrome.
Upon multivariate analyses, body mass index was the most important independent predictor of ALT levels in both groups. The odds ratio for an abnormal or elevated ALT level was 2.2 for children and 1.8 for adolescents with BMIs above the 75th percentile for age, gender, and race. Other significant independent predictors were white race in children; and total cholesterol to HDL cholesterol ratio, HOMA-IR, and male gender in adolescents.