Hepatitis C virus (HCV) can cause a range of kidney diseases. HCV is the primary cause of mixed cryoglobulinaemia, which leads to cryoglobulinaemic vasculitis and cryoglobulinaemic glomerulonephritis (GN). Patients with acute cryoglobulinaemic vasculitis often exhibit acute kidney disease due to HCV infection, which typically progresses to acute kidney injury (AKI). HCV also increases the risk of chronic kidney disease (CKD) and the likelihood of developing end-stage renal disease (ESRD). Currently, direct-acting antiviral agents (DAAs) can be used to treat kidney disease at different stages. This review focuses on key findings regarding HCV and kidney disease, discusses the impact of DAAs, and highlights the need for further research and treatment.

OBJECTIVE: This study aims to observe the clinical efficacy of low-dose rituximab in patients with cryoglobulinaemia secondary to connective tissue diseases.
METHODS: Rituximab (100 mg) was infused in patients once a week for four weeks, combined with prednisone (20 mg) once a day, and reduced regularly. Treatment effect was observed regularly.
RESULTS: Joint pain, fever, rash and fatigue symptoms in patients eased. The serology (globulin, erythrocyte sedimentation rate, C-reactive protein, lactate dehydrogenase and others) parameters returned to normal.
CONCLUSIONS: Low-dose rituximab therapy for cryoglobulinaemia secondary to connective tissue diseases was safe and effective, and can be used as a treatment option in this condition.

OBJECTIVE: Cryoglobulinaemic glomerulonephritis related to hepatitis B virus (HBV) infection has been rarely reported. The aim of this study was to investigate the clinical features, renal biopsy findings in patients with HBV-associated cryoglobulinaemia.
METHODS: Twelve patients with HBV-associated cryoglobulinaemia were identified in this study. The demographic, clinical, pathological characteristics, treatment and follow-up data were analyzed.
RESULTS: Renal involvement was characterized by nephrotic range proteinuria with microscopic haematuria in all patients, and impaired renal function in nine patients (75%). Purpuric rash was the main extrarenal manifestation (58.3%). Type II cryoglobulinaemia was presented in three patients and type III in nine patients. Hypocomplementaemia and positive of rheumatoid factors were present in all patients. Membranoproliferative glomerulonephritis (MPGN) was observed in all kidney specimens. Seven patients also had evidence of prominent cryoglobulins thrombi on renal biopsy, but only three patients had HBV antigen deposits in renal tissues. Antiviral and steroids or immunosuppressive agents have been used in most of patients. During follow-up, two patients died, and four reaching end-stage renal disease; three patients had complete remission, and three patients had renal function improved after therapy.
CONCLUSIONS: Nephrotic syndrome with haematuria and renal insufficiency are the main clinical manifestation; cryoglobulinaemic glomerulonephritis are the main renal lesion in patients with HBV-Associated cryoglobulinaemia; half of patients have poor outcome even with antiviral and immunosuppressive therapy. The results of this study indicate that cryoglobulins should be detected in hepatitis B virus-Associated nephropathy in endemic area.