Normal serum alanine aminotransferase activity in uncomplicated obesity.

OBJECTIVE

To evaluate serum alanine aminotransferase (ALT) activity in a well-characterized group of uncomplicated obese subjects and its correlation with insulin resistance, plasma adiponectin, and leptin concentrations.

METHODS

One hundred and five uncomplicated obese subjects (87 women, 18 men, age 34.3+/-9.6 years, BMI 39.9+/-8.3 kg/m(2)) were studied. Serum ALT activity was evaluated. Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp (M index) and fasting insulin. Plasma leptin and adiponectin levels were also measured.

RESULTS

Serum ALT concentration in the whole group of uncomplicated obese subjects was 17.73+/-6.33 U/L with none of the subjects presenting ALT levels greater than 43 U/L and only 9 (11%) women and 3 (19%) men showed ALT levels >19 and >30 U/L for women and men, respectively. No significant difference was detected in serum ALT levels between severe obese subjects (BMI >40 kg/m(2)) and those with BMI <40 kg/m(2) (18.63+/-6.25 vs 17.26+/-6.02 U/L). ALT was significantly correlated with fasting insulin (r = 0.485, P = 0.02) and triglycerides (r = 0.358, P = 0.03).

CONCLUSIONS

Serum ALT activity is practically normal in uncomplicated obese subjects, independently of their obesity degree. These findings suggest the role of obesity-related comorbidities and not of BMI as main risk factors for elevated ALT levels in obese subjects.