Evaluation of radioimmunoassays using mono- and polyclonal antibodies for the quantitation of human chorionic gonadotropin in early pregnancy.

Five commercial kits for the quantitative determination of human chorionic gonadotropin (hCG) were evaluated for use in an In Vitro Fertilization program. We focused on practicability, precision, sensitivity and the early detection of pregnancy. The IRE method uses purified antiserum against complete hCG and requires overnight incubation. Precision is poor but hCG results agree closely with the other assays. Three other kits use a beta-subunit specific antiserum (Amersham, Becton-Dickinson, Clinical Assays). All these assays have acceptable precision especially in their mid-range. The Amersham assay has the shortest assay time, while the Clinical Assays method requires the least manipulation. The Becton Dickinson assay is precise, less sensitive and has the highest frequency of slightly elevated hCG levels in males and non pregnant females. The Hybritech kit is an immunoradiometric assay based on two monoclonal antibodies. It was tested with a two-step incubation procedure needing a longer assay time than the beta-subunit specific assays but it has the best precision at low hCG levels and is the most sensitive test with the least interference in samples obtained from males and non-pregnant females. For the early detection of pregnancy all assays performed equally well.