Comparison of Serum Ferritin and Vitamin D in Association with the Severity of Nonalcoholic Fatty Liver Disease in Korean Adults

BACKGROUND Increased serum ferritin and decreased vitamin D levels associated with nonalcoholic fatty liver disease (NAFLD). However, their association with the severity of NAFLD has not been fully evaluated. The aim of this study was to compare the association of serum ferritin and 25(OH)D₃ levels with the severity of ultrasonographically detected NAFLD (US-NAFLD) and hepatic steatosis defined by fatty liver index (FLI) in Korean adults. METHODS A cross-sectional analysis of clinical and anthropometric data, including serum ferritin and 25(OH)D₃, from men (n=295) and women (n=263) who underwent a routine health check-up in 2012. RESULTS In men, with an increase in the quartile of serum ferritin level, the incidences of subjects with metabolic syndrome (P=0.002), US-NAFLD (P=0.041), and FLI ≥60 (P=0.010) were significantly elevated. In women, the incidence of subjects with US-NAFLD was also significantly elevated with increases in the serum ferritin quartile (P=0.012). Regarding 25(OH)D₃, no statistical differences were observed among the different quartiles in either gender. Serum ferritin level significantly increased as the severity of US-NAFLD increased (P<0.001); however, no significant differences in 25(OH)D₃ level were observed in men. No significant differences in either serum ferritin or 25(OH)D₃ level were observed among women with different levels of severity of US-NAFLD. CONCLUSION Increased serum ferritin level showed a closer association with severity of NAFLD compared with level of serum vitamin D, suggesting that serum ferritin level may be a better marker than vitamin D level for predicting the severity of US-NAFLD and hepatic steatosis in a clinical setting.