Childhood obesity increases the risk of non-alcoholic fatty liver disease marked by elevated alanine aminotransferase (ALT). This study investigated the prevalence of increased ALT in children and adolescents with obesity, and its associations with sex, age, degree of obesity, and metabolic parameters.
Individuals between 5 and 17.99 years of age enrolled in the Swedish Childhood Obesity Treatment Register (BORIS) before March 2020 were included. Mildly increased ALT was defined by ALT 27–51 U/L (males) and 23–43 U/L (females), while markedly increased ALT by levels above. Multiple logistic regression models were used for statistical analysis.
Among 11,776 individuals (age 11.0 ± 3.3 years, 53.5% males), the prevalence of mildly and markedly increased ALT were 37.9 and 10.6%, respectively. A sex-age interaction was found, where increasing age strengthened the odds of markedly increased ALT in males (OR, 99% CI: 1.34, 1.29–1.4 for each year) while the corresponding pattern in females with was minuscule (1.09, 1.02–1.10). Compared to class I obesity, class II and III obesity had greater odds ratios for mildly increased ALT (class II obesity OR, 99% CI: 1.51, 1.35–1.70; class III obesity OR, 99% CI: 2.17, 1.66–2.61) and for markedly increased ALT (class II obesity OR, 99% CI: 1.82, 1.51–2.20; class III obesity OR, 99% CI 3.38, 2.71–4.23). Dyslipidemia was associated with both mildly and markedly increased ALT, all p < 0.001. Prevalence of impaired fasting glucose was 19.1% in normal ALT group, 20.4% in mildly increased ALT group, and 29.0% in markedly increased ALT group.
The risk of markedly increased ALT increased exponentially with age among boys, but not among girls. Higher degree of obesity was observed in individuals with mildly and markedly increased ALT. Further, metabolic derangements were more prevalent among individuals with mildly and markedly increased ALT.