Serum cystatin C is an early renal dysfunction biomarker in patients with hepatitis C virus

BACKGROUND: Hepatitis C virus (HCV) may induce extrahepatic manifestations as acute or chronic renal dysfunction. The aim was to evaluate the diagnostic role of some biomarkers as cystatin C, cryoglobulins, rheumatoid factor (RF), and complement C3 for extrahepatic renal affection in newly diagnosed patients with HCV infection. METHODS: Blood and urine were collected from randomized individuals screened for new HCV infection (n=400). The studied populations were divided into 3 groups: control group I: thirty healthy individuals not suffering from either liver or kidney diseases, group IIa: thirty HCV patients who have positive HCV antibody test but showed negative PCR test, and group IIb: thirty HCV patients who showed positive results for both HCV antibody and PCR tests. RESULTS: In HCV group IIb, levels of serum total bilirubin, AST and ALT, and urine albumin/creatinine ratio were increased whereas serum albumin and creatinine clearance were decreased versus other groups. However, the levels of blood urea nitrogen and serum creatinine were still within the normal range in all groups. In HCV group IIb, cystatin C, cryoglobulins, and RF levels were increased; meanwhile, serum creatinine/cystatin C ratio and complement 3 levels were decreased compared to the other groups. HCV-infected patients significantly had higher serum cystatin C (>1.24 mg/L, P<0.001) and lower creatinine/cystatin C ratio (<70.1μMol/mg, P=0.002), and cystatin C was significantly correlated with liver and kidney parameters. CONCLUSION: High serum cystatin C and low creatinine/cystatin C ratio may be early indicators of mild renal dysfunction with normal serum levels of creatinine in HCV-infected individuals.