Background: We studied the associations of clustering of metabolic risk factors with plasma levels of alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT) in healthy prepubertal children.
Methods: The subjects were a representative population sample of 492 children 6-8 years of age. We assessed body fat percentage (dual-energy X-ray absorptiometry), body mass index, waist circumference, systolic and diastolic blood pressure, glucose, insulin, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, ALT, GGT, and high-sensitivity C-reactive protein (hsCRP) and calculated a continuous metabolic syndrome score variable. We also used factor analysis to examine whether high-normal liver enzymes are a feature of metabolic syndrome among children.
Results: Children with overweight or obesity, defined by International Obesity Task Force (IOTF) criteria, had a 2.1-times higher risk of having ALT and a 4.5-times higher risk of having GGT in the highest fifth of its distribution than normal weight children. Children in the highest sex-specific third of metabolic syndrome score, body fat percentage, waist circumference, and insulin had a two to three times higher risk of being in the highest fifth of ALT and GGT. Moreover, children in the highest third of glucose and hsCRP had a 2.5-fold risk of being in the highest fifth of GGT. First-order factor analysis yielded three factors; the first included insulin, glucose, and triglycerides; the second waist circumference, insulin, GGT, and hsCRP; and the third HDL-C, triglycerides, waist circumference, and insulin. Second-order factor analysis yielded a single metabolic syndrome factor, explaining 64.1% of the variance.
Conclusions: Clustering of metabolic risk factors, particularly excess body fat, is associated with high-normal levels of ALT and GGT in prepubertal children. High-normal levels of liver enzymes, especially GGT, and systemic low-grade inflammation could be considered features of metabolic syndrome among children. Subtle changes in liver function may play an important role in the pathogenesis of metabolic syndrome beginning in childhood.