Histological changes in the liver of morbidly obese patients: correlation with metabolic parameters

Obesity is a major risk factor for fatty liver disease. The purpose of this study was: 1) to determine the degree of steatosis, inflammation and fibrosis in liver biopsies of morbidly obese patients in relation to their body fat distribution and metabolic status, and 2) to examine the course of liver enzyme changes with surgically-induced weight loss.

The study population included 179 morbidly obese bariatric surgical patients (82% female, 18% male, mean age 39+/-0.7 (SEM) years, BMI 52+/-0.6 kg/m2, excess body weight 80+/-1.8 kg). All patients tested negative for hepatitis and HIV. Liver biopsies were taken intra-operatively. Hepatic enzyme activities were measured along with lipid parameters, fasting glucose, insulin and leptin.

Liver biopsies showed that 47% of morbidly obese females and 85% of males had >30% of hepatocytes filled with fat droplets. Clinically significant hepatic steatosis was associated (P<0.01) with: a) metabolic aberrations, i.e.hyperlipidemia, hyperglycemia, b) male gender, c) abdominal adiposity, and d) elevated hepatic aminotransferase activities. Hepatic inflammation was found in 47% of females and 55% of males, and 'moderate' fibrosis occurred in 12% of males and 6% of females. Postoperatively, the activity of hepatic aminotransferases declined after an initial increase in response to weight loss, with normalization of values occurring at an excess weight loss of 50% (P<0.0001).

The majority of morbidly obese patients have >30% steatosis of the liver. The incidence of steatosis is higher for males than females, possibly due to their visceral obesity and associated metabolic aberrations.