The fluctuations of hepatitis C virus RNA and IgM anti-HCV (core) serum levels correlate with those of alanine aminotransferases during the hepatitis relapses of patients treated with interferon.

Variations in the serum levels of hepatitis C virus (HCV) RNA. IgM antibody against the HCV 'core' structural protein (c22) and alanine amino-transferase (ALT) were measured in 23 patients with chronic hepatitis C who underwent therapy with interferon-alpha 2a (IFN alpha 2a). Low pretreatment levels of viraemia and undetectable IgM anti-core were significantly associated with a long-term response to treatment. In patients with hepatitis relapses after the end of treatment, HCV RNA levels increased before or at the same time as ALT in 29 out of 34 cases (85%). ALT flares occurred before or simultaneously with IgM anti-core elevations in 18 out of 20 cases (90%). Therefore, post-treatment hepatitis C exacerbations show the same sequence of events seen as in hepatitis B exacerbations (increases of viraemia followed by those of ALT and IgM anti-'core'). These findings underscore the diagnostic and prognostic usefulness of monitoring anti-HCV-positive patients with quantitative assays for HCV markers.