Variance in the transaminase levels over the body mass index spectrum in 10- and 13-year-olds.

BACKGROUND

Transaminase levels increase with body mass index (BMI) and also with an extreme drop in the BMI, as in the case of patients with anorexia nervosa. We examined these levels over the BMI spectrum in Japanese 10- and 13-year-olds.

METHODS

Fifth- and eighth-grade students (n= 3747) from all schools in Shunan City, Japan, between 2006 and 2008 were included in the study. BMI z-score and serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyltransferase (GGT) were measured.

RESULTS

The ALT and GGT levels increased with z-BMI values in the boys and 10-year-old girls (P≤ 0.001). In the 13-year-old girls, only the ALT levels increased with the z-BMI values (P= 0.018). Similarly, the proportion of subjects with elevated ALT and GGT levels increased with the z-BMI values (p(trend) < 0.05). The AST levels were negatively associated with BMI in the girls (P < 0.001). Among the boys, these levels were elevated at the highest z-BMI values and slightly elevated at lower values, but not significantly. These associations did not change after adjustments for confounders. Generalized additive model analyses revealed that transaminase had non-linear relationships with z-BMI, except for the AST levels in the girls.

CONCLUSION

The elevated ALT and GGT levels were associated with high BMI in both sexes. In the same study population, however, AST increased in the girls with low BMI and in the boys with high BMI.