Serum thioredoxin elucidates the significance of serum ferritin as a marker of oxidative stress in chronic liver diseases

BACKGROUND/AIMS: Serum thioredoxin (TRX) levels have recently been established as an indicator of oxidative stress in various diseases. The aim of the present study was to clarify the clinical significance of serum ferritin in chronic liver diseases. METHODS: Levels of ferritin, transferrin saturation (TS), aspartate aminotransferase (AST), and TRX were measured in the sera of patients with chronic hepatitis C (CH-C, n=92), chronic hepatitis B (CH-B, n=28), nonalcoholic fatty liver (FL, n=31), or alcoholic liver diseases (ALD, n=17). Serum TRX levels were evaluated with a recently established sandwich enzyme-linked immunosorbent assay kit. RESULTS: Serum TRX levels were significantly higher in CH-C, FL, and ALD than in healthy volunteers. A larger proportion of patients with CH-C, FL, and ALD had elevated levels of serum ferritin than CH-B. Serum ferritin levels were positively correlated with levels of TS, AST, and TRX in CH-C, but were merely correlated with TS values in CH-B. Ferritin levels were also well correlated with AST and TRX, but not with TS in FL and ALD. CONCLUSION: Oxidative stress, which was evaluated by measuring serum TRX, in addition to storage iron and hepatocyte damage is a cause of increasing serum ferritin levels in chronic liver diseases. An elevated serum ferritin level, which was correlated with TS, indicates that iron-induced oxidative stress contributes to CH-C. Elevated ferritin levels in FL and ALD may be mostly due to iron-unrelated stresses.