Human chorionic gonadotropin and its subunits in hydatidiform mole and choriocarcinoma

Serum human chorionic gonadotropin (hCG) was measured by a radioreceptorassay (RRA) and radioimmunoassay (RIA) and serum hCG-beta and hCG-alpha by RIA in 10 patients with intact mole, 3 patients with choriocarcinoma, and 4 patients with hydatidiform mole during treatment. hCG levels by RRA were higher in 5 of 10 molar pregnancies and ranged from 20,900 to 100,000 ng/ml and from 30,000 to 100,000 ng/ml by RIA. hCG levels by RRA and RIA paralleled one another closely during treatment of hydatidiform mole. hCG-alpha was higher than hCG by RRA and RIA and hCG-beta in molar pregnancies, in the uterine venous blood draining a uterine choriocarcinoma, and during chemotherapy of choriocarcinoma. In 2 of 3 choriocarcinoma patients who eventually developed cerebral metastases, hCG-alpha increased while hCG and hCG-beta were declining or negative. hCG-beta was usually lower than hCG or hCG-alpha in all the cases studied. These results demonstrate the production of free alpha and beta subunits in trophoblastic disease. Further, due to the biospecificity, simplicity, and rapidity, the RRA of hCG is a sueful diagnostic aid during treatment of trophoblastic neoplasia until the levels fall to within the sensitivity range of the assay. Finally, the RIA of hCG, hCG-beta, and hCG-alpha, which requires several days, should be performed until they become negative or fall within normal range.