Iron load and liver enzymes in 10- and 13-year-olds

Iron plays a pivotal role in adult steatosis, but its role in child and adolescent steatosis is unclear. We investigated the effect of dietary iron, serum iron, and ferritin on serum transaminases and γ-glutamyltransferase in 10- and 13-year-olds.

The study included 4894 fifth and eighth graders enrolled between 2006 and 2009 in all schools in Shunan City, Japan. Multiple regression analyses were performed with adjustments for grade, sex, z score of the body mass index, serum lipids, plasma glucose, frequency of sports activities, having a single parent, number of siblings, tobacco smoking behavior, passive smoking at home, resident areas, and schools, using linear mixed models. In addition, we analyzed ferritin and insulin resistance in randomly selected subset of participants.

Dietary iron intake was positively associated with serum alanine aminotransferase levels (standardized coefficient β = 2.35, P = 0.019). Serum iron concentrations were associated with transaminase and γ-glutamyltransferase levels (β = 3.22, and 4.05, respectively, P < 0.01). In the subset of 421 subjects with further serum analysis, serum ferritin levels were significantly associated with serum enzyme levels (β = 2.43-3.35; P < 0.05) and showed significant odds ratio for the elevated alanine aminotransferase levels (1.05 for 1 SD with 95% confidence intervals 1.02-1.08). However, iron load did not show a positive association with insulin resistance.

Although an effect size for iron is small in regression analyses, iron is implicated in increased transaminase levels in prepubertal and pubertal children.