Serum prolactin levels and immunohistochemical localization of prolactin in trophoblastic disease.

The circulating levels of chorionic gonadotropin, pregnancy specific beta-I-glycoprotein, prolactin and oestradiol were estimated by radioimmunoassay in 219 serum samples from 18 patients with choriocarcinoma and 45 samples from 8 patients with hydatidiform mole. Prolactin and oestradiol concentrations were higher in samples which also contained trophoblastic markers. This difference was also seen in patients with choriocarcinoma and it was not due to chemotherapy, since the difference between hCG positive and hCG negative samples was maintained during chemotherapy. Prolactin was found by immunoperoxidase technique in the syncytiotrophoblast of normal placenta throughout gestation, and also in hydatidiform mole, invasive mole and choriocarcinoma. It is suggested that the malignant syncytiotrophoblast may contribute to circulating prolactin levels either by direct secretion of prolactin or by oestrogen stimulation of the pituitary.