Serum leptin levels in patients with nonalcoholic chronic liver disease

The elevated serum leptin level of patients with alcoholic cirrhosis has been reported, however, the precise mechanism is still unknown. Leptin expression and protein synthesis have also been detected in activated hepatic stellate cells in cell cultures, which play a major role in hepatic fibrosis. We evaluated the serum leptin levels of patients with nonalcoholic liver diseases including cirrhosis and chronic hepatitis. We also investigated the hepatic clearance of leptin by determining the serum leptin level in blood samples obtained from the portal and hepatic veins.

The serum leptin level of 44 patients with nonalcoholic chronic liver disease (male/female = 21/23, cirrhosis/chronic hepatitis = 30/14) and 40 control subjects (male/female = 20/20) was determined in blood samples obtained from the antecubital vein by enzyme-linked immunosorbent assay. We also assessed the relationship between the leptin level and various biochemical tests of liver function. Additionally, we determined the leptin levels in the portal and the hepatic venous blood (nonalcoholic cirrhosis = 10, nonhepatic disease = 4).

There were positive correlations between the serum leptin level and body mass index among males and among females in the liver disease group and in the control group. However, the serum leptin level of the liver disease group and control group did not differ significantly. Among the 44 liver disease patients, only the serum cholesterol level was significantly correlated with the serum leptin level after adjusting for sex and body mass index by multiple regression analysis. Furthermore, the leptin level in hepatic venous blood was significantly lower than that in portal venous blood. However, the ratio of [leptin level in hepatic venous blood]/[leptin level in portal venous blood] in the cirrhosis group, and that in the nonhepatic disease group, did not significantly differ.

The serum leptin level of patients with nonalcoholic liver diseases is not elevated. On the other hand, the serum leptin level of patients with alcoholic cirrhosis has been reported to be elevated. The difference in the serum leptin level of patients with nonalcoholic liver disease and that of patients with alcoholic cirrhosis may be due to a difference in factors such as the levels of cytokines or sex steroids, and/or nutrition. Furthermore, it is likely that leptin is cleared in part by the portosystemic circulation through the liver.