Detection of a small molecular species of human chorionic gonadotropin in the urine of patients with carcinoma of the cervix and cervical intraepithelial neoplasia: comparison with other assays for human chorionic gonadotropin and its fragments.

A low-molecular-weight glycoprotein containing sequences of the beta subunit of human chorionic gonadotropin (hCG) has been found in the urine of patients with carcinoma of the cervix using an immunoradiometric assay. This fragment has chromatographic and immunological identity with hCG beta core. This molecule was present in 52 to 77% of all patients with invasive disease, while between 11 and 27% of patients with cervical intraepithelial neoplasia (CIN) also exhibited significant hCG beta-core immunoactivity. Few patients had either a positive assay for intact hCG or a positive assay directed at an epitope on the beta subunit (beta-hCG radioimmunoassay) in serum. However, between 17 and 40% of patients with invasive disease were positive for free beta-subunit immunoactivity in the blood. The origin of the beta-core immunoactivity in the urine is uncertain; while tumor production cannot be excluded, it is possible that the molecule originates from renal metabolism of small quantities of the beta subunit of hCG. Regardless of the source of the molecule, hCG beta core is a far more sensitive marker of hCG production by tumors than is serum hCG.