Human chorionic gonadotropin, its free subunits and gestational trophoblastic disease.

Monoclonal antibody-based immunoassays can detect specifically intact human chorionic gonadotropin (hCG), the free alpha-subunit and the free beta-subunit. The differential production of hCG and its free subunits is important in gestational trophoblastic disease. Using well-defined epitope-specific monoclonal antibodies in an immunoradiometric assay format, specific and sensitive assays have been developed. Serum levels of free beta-hCG were abnormally high in patients with gestational trophoblastic disease. In contrast, free alpha-hCG levels in serum were not increased.