Weight loss and non-alcoholic fatty liver disease: falls in gamma-glutamyl transferase concentrations are associated with histologic improvement.

BACKGROUND: The ability for aminotransferase levels to track histological features of non-alcoholic fatty liver disease (NAFLD) with weight loss has not been examined.
METHODS: We examined the effect of weight loss following laparoscopic adjustable gastric banding surgery on the histological features of NAFLD and plasma aminotransferase concentrations (AST, ALT and GGT) in 60 (12M, 48F) selected severely obese patients. All 120 paired biopsies were de-identified and scored for lobular steatosis, fibrosis, inflammation, Mallory bodies and NASH.
RESULTS: 30 patients (50%) had baseline histological features of non-alcoholic steatohepatitis (NASH). Repeat biopsies were taken at 29.5+/-10 months after baseline. Mean weight loss was 31.5+/-18 kg. There were improvements in AST, ALT, GGT, lobular steatosis, inflammation and fibrosis between baseline and follow-up (P<0.001 for all). Only 6 (10%) of repeat biopsies showed NASH. No change in aminotransferase concentrations predicted the change in steatosis, but changes in AST and GGT predicted improved scores for inflammation, fibrosis, Mallory bodies and NASH. The lowering of GGT best predicted the improvements in inflammation, fibrosis and NASH.
CONCLUSION: With weight loss, falls in GGT and, to a lesser extent, in AST, are predictive of improved lobular inflammation and fibrosis, key prognostic features of NAFLD.