Serum retinol-binding protein 4 levels are elevated in non-alcoholic fatty liver disease

OBJECTIVE Retinol-binding protein 4 (RBP4) is a recently identified adipokine that is elevated in the serum in several insulin-resistant states. We investigated the relationship between non-alcoholic fatty liver disease (NAFLD) and serum RBP4 in nondiabetic adults. METHODS One hundred and fifty-nine nondiabetic, non-alcoholic subjects (95 males and 64 females) participated in this study. Division of subjects into a NAFLD group (n = 73; 45 males and 28 females) or a normal group (n = 86; 50 males and 36 females) was based on the presence of fatty liver disease determined by sonography. RESULTS Serum RBP4 levels in the NAFLD group were significantly higher than those in the normal group (62.8 +/- 16.0 mg/l vs. 51.7 +/- 14.6 mg/l, P < 0.0001). Multiple logistic regression analysis revealed that the RBP4 level was an independent factor associated with NAFLD (P = 0.0042). In addition, serum RBP4 levels were positively correlated with serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltranspeptidase (GGT) levels. The significant association between serum RBP4 and GGT levels remained even after adjusting for age, gender, body mass index, the homeostasis model of assessment (HOMA) value and the presence of NAFLD (r = 0.3097, P = 0.0002). CONCLUSION Serum RBP4 levels are significantly associated with NAFLD and liver enzymes.