Serum prolactin response to thyrotropin-releasing hormone and metoclopramide in patients with prolactin-secreting tumors before and after transsphenoidal surgery

7 female patients with amenorrhea, galactorrhea, and hyperprolactinemia were examined before and after selective transsphenoidal removal of a PRL-secreting microadenoma. Before adenomectomy, metoclopramide (MCP; 10 mg orally) and TRH (200 μg iv) did not increase PRL blood levels in any of the 7 patients. On the contrary, after oral administration of 10 mg MCP, a positive response was noted in a group of 8 lactating women 3 days postpartum. After surgery, serum PRL level returned to normal in all patients. A positive PRL response to MCP and TRH was found in 6 of the 7 patients 1 mth after surgery. One patient, who had the lowest PRL level, failed to show a PRL increase after both stimuli. These findings indicate that hypothalamic pituitary function can be restored to normal after transsphenoidal removal of PRL-secreting pituitary tumors.