[Laboratory diagnosis of hepatitis C]

Laboratory algorithm for the diagnosis of viral hepatitis C (HVC) is proposed. Blood sera are screened for antiHVC by third-generation EIA and PCR of HVC RNA. Positive result of PCR is diagnostically significant. In case of positive EIA and negative PCR the serum is to be analyzed in immunoblotting. If immunoblotting is not carried out, the diagnosis is made on the basis of estimated values of hepatitis C probability attached to diagnostic EIA kit used in clinical laboratory. When evaluating the positive result, the increase in optic density (OD) of analyzed samples is compared with the cutoff OD. In OD higher than 9 and below 1.5 the probability of disease is 92.6 and 11.8%, respectively. Patients with doubtful results of serological tests are to be regularly checked up for 1 year, with laboratory tests (immunoblotting and PCR) repeated every 3 months. Complex laboratory diagnosis by biochemical and serological methods and PCR should be carried out in groups at a high risk of HVC.