Renal manifestations associated with hepatitis C virus.

Among the several types of chronic glomerulonephritis (GN) described in association with hepatitis C virus (HCV) infection, cryoglobulinemic glomerulonephritis is by far the most frequent. It is usually associated with type II cryoglobulinemia with IgM k rheumatoid factor. It is a membranoproliferative GN, which shows some distinctive histologic features (intraglomerular monocyte infiltration, intraluminal thrombi due to massive precipitation of cryoglobulins, renal vasculitis), has a chronic course with acute recurrent episodes that can be controlled by corticosteroids more than by antiviral therapy (interferon alpha). More controversial is the association with type I non-cryoglobulinemic membranoproliferative GN, which has been found in some series from the USA and Japan but not in others. The demonstration of HCV antibodies and/or HCV-RNA in other types of chronic glomerulonephritis is usually reported in a small minority of cases suggesting the possibility of a coincidental finding more than an etiologic factor.