Introduction: Fibroblast growth factor-21 (FGF21) regulates glucose, lipid, and energy homeostasis. Retinol-binding protein-4 (RBP4) controls metabolic and proliferative cell functions.
Aims and methods: Aims of the study were to assess (1) serum FGF21 and RBP4 levels in 75 non-obese chronic hepatitis C (CHC) patients and 41 healthy controls similar in age and BMI; (2) the relationship between their serum concentration and insulin resistance, liver histology, and biochemical parameters; (3) their effectiveness as diagnostic markers.
Results: FGF21 levels increased significantly in CHC patients compared with controls (p = 0.04). CHC patients with steatosis had significantly higher FGF21 levels compared with those without steatosis (p = 0.01). FGF21 concentration was positively related to steatosis grade (r = 0.39, p = 0.007). RBP4 levels did not differ between CHC patients and controls, but were negatively associated with necro-inflammatory activity grade (r = (-0.34), p = 0.04), with significantly higher levels in patients with minimal inflammatory activity (G1 vs. G2/3, p < 0.001; G1 vs. G2, p = 0 < 001; G1 vs. G3, p = 0.01). After stepwise linear regression analysis adjusting for potential confounders, RBP4 levels retained their independent significance as a predictor of necro-inflammatory activity (β = -0.31; t = -2.15, p = 0.035) and FGF21 levels as a predictor of steatosis (β = 0.34; t = 2.31, p = 0.024). Serum FGF21 correlated with serum RBP4 levels (r = 0.32, p = 0.02).
Conclusions: Serum FGF21 levels increased in CHC patients, especially in those with steatosis and were associated with steatosis grade. FGF21 seems to be a useful diagnostic marker in determining hepatic steatosis in CHC. A negative association between serum RBP4 and necro-inflammatory activity indicates that disease severity may determine RBP4 levels.