Association between elevated serum hepatic enzyme activity and total body fat in obese humans

To investigate the associations between obesity and serum hepatic enzyme activities, we measured total body fat (TBF), body mass index (BMI), and hepatic biochemical parameters in 732 apparently healthy adults. TBF was assessed using a body fat analyzer. Serum activities of alanine and aspartate aminotransferase (ALT and AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and lactate dehydrogenase (LD) were determined by standard spectrophotometric methods. Mean activities (+/- SD) of serum ALT and AST in men with high fatness were 51.2 +/- 12.6 U/L and 32.9 +/- 9.2 U/L, which were significantly higher than those in men with low fatness (23.5 +/- 7.4 U/L and 22.5 +/- 7.8 U/L, p < 0.01). Of 147 men with high fatness, 56 (38.1%) had serum ALT levels above the upper limit of normal, whereas only 9.5% (31/328) of men with low or desirable fatness showed elevated serum ALT activities (p < 0.01). Serum ALT, AST, and GGT activities correlated significantly with TBF in both overweight men and women. Among subjects having high TBF, those with fatty liver showed significantly higher incidence of elevated hepatic enzymes, compared to those without fatty liver. In short, elevated serum hepatic enzyme activities are associated with TBF and a high prevalence of fatty liver is observed in subjects with elevated TBF.