Serum retinol-binding protein 4 levels in patients with nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD), one of the most common forms of chronic liver disease, is closely associated with obesity and insulin resistance (IR). Recent studies suggest serum retinol-binding protein 4 (RBP4) plays a key role in the pathogenesis of IR. The aims of this study were to determine serum RBP4 levels in patients with biopsy proven NAFLD, and to correlate these levels with the metabolic profile and histologic features in this population.
METHODS: Our cohort consisted of 51 consecutive patients undergoing liver biopsy for clinical suspicion of NAFLD. Patients were subsequently divided into 3 groups: simple steatosis (n=16), borderline nonalcoholic steatohepatitis (NASH) (n=2) and NASH (n=33). The stage of fibrosis was measured using a 4-point scale. RBP4 was measured in triplicates by a specific enzyme-linked immunosorbent assay. The degree of insulin resistance was determined by the homeostatic model assessment.
RESULTS: Serum RBP4 levels did not correlate with body mass index, homeostatic model assessment, fasting glucose, or insulin levels in patients with simple steatosis and NASH. Moreover, RBP4 levels were lower in patients with NASH compared with those with simple steatosis (21.3 and 26.8 mg/L, respectively) although the difference did not reach statistical significance (P=0.21). A stepwise decrease in RBP4 levels from patients without fibrosis (27.9 mg/L) to patients with cirrhosis (14.1 mg/L) was noted (P=0.03).
CONCLUSIONS: Our study demonstrates that in adult patients with NAFLD, serum RBP4 levels do not correlate with body mass index or insulin resistance and identifies a novel association between serum RBP4 levels and hepatocellular injury in these patients.