Association of adiposity, measures of metabolic dysregulation, and elevated alanine aminotransferase in subjects with normal body mass index

Background: Differences in body fat (BF) distribution in patients with normal body mass index (BMI) with elevated alanine aminotransferase (ALT) remains poorly described.

Objective: To determine the relationship between total BF, waist circumference (WC), insulin resistance (IR), and cardiometabolic risk profile in subjects with elevated ALT and normal BMI.

Methods: We analyzed cross-sectional data from 4,914 US participants in the third National Health and Nutrition Examination Survey database, who were ≥20 years of age, had normal BMI, and had body composition assessed by bioimpedance.

Results: Mean ± SD age was 41.4 ± 0.3 years, and 58% participants were women. BF was 20 ± 0.1% in men and 29.9 ± 0.1% in women. As total BF increased by tertiles, there was a tendency towards a higher prevalence of nonalcoholic fatty liver disease in men (6.1%, 6.5%, 9.5%, P = 0.13), but not in women (8.7%, 8.2%, 10.7%, P = 0.71). As WC increased by tertiles, there was a higher prevalence of elevated ALT in men (2.6%, 8.6%, 6.6%, P < 0.0001), but not in women. As ALT increased, men had significantly higher levels of nonhigh density lipoprotein cholesterol (HDL-C), increased apolipoprotein B, increased IR, and lower levels of C-reactive protein, whereas, women had higher levels of non-HDL-C and increased IR.

Conclusion: In subjects with normal BMI, increased WC is associated with a higher prevalence of elevated ALT in men, but not in women. Higher levels of ALT correlated with a poor cardiometabolic risk profile.