Persistent Defect in Regulation of Prolactin Secretion after Successful Pituitary Tumor Removal in Women with the Galactorrhea-Amenorrhea Syndrome*

Abstract

TRH, metoclopramide (MCP), chlorpromazine (CPZ), and insulin (ITT) stimulation tests of PRL secretion were carried out in age-matched controls and before and after successful removal of pituitary prolactinomas in women with the galactorrhea-amenorrhea syndrome. In preoperative patients there was a blunted or absent PRL response to TRH in 87%, to MCP in 100%, to CPZ in 100%, and to ITT in 93%. Two to 6 months after successful tumor removal, serum PRL rose 2-fold (the usual criterion for a normal response) in 73% after TRH, in 100% after MCP, but in only 13% after CPZ and in only 14% on ITT. However, the PRL increment with all four tests was significantly lower than that in normal controls. One to 8 yr after successful surgery, the PRL increments after TRH and MCP were returning to normal, but the PRL responses to CPZ and ITT remained blunted. GH, ACTH, and TSH reserves were intact in all patients. The diminished PRL response to all stimulation tests observed up to 6 months postoperatively might be explained by the persistence of a negative feedback effect from high PRL levels associated with the tumor. The more persistent impairment of the PRL response to CPZ and ITT is unexplained but suggests a hypothalamic defect.

Persistence of impaired PRL responses to sulpiride in patients with PRL secreting pituitary adenomas after successful hypophysectomy.

“…The normalization of PRL-responses to TRH after successful hypophysectomy confirms the previous reports (Barbarino et al 1979;Tucker et al 1980;Schlechte and Sherman 1981), although these authors could not observe the distinct responses before the surgery.…”

“…Therefore, if the pituitary tumor was removed completely , the recovery of normal lactotrophs from the tumor compression and of PRL responsiveness to exogenous stimuli would be expected. Although there are several reports regarding the changes of responsiveness after hypophysectomy, the results are not always consistent (Barbarino et al 1979; Murray et al 1979;Tucker et al 1980; Schlechte and Sherman 1981).…”

“…PRL-noma usually shows reduced or blunted responsiveness of plasma PRL to several agents (Barbarino et al 1978;Jeske 1979;Cowden et al 1979; Tucker et al 1980). Therefore, if the pituitary tumor was removed completely , the recovery of normal lactotrophs from the tumor compression and of PRL responsiveness to exogenous stimuli would be expected.…”

Hyperprolactinemia

“…The provocative agents included thyrotropin releasing hormone (TRH), chlorpromazine, levodopa, carbidopa, domperidone, nomifensine and insulin induced hypoglycemia [24][25][26][27][28][29][30]. Unfortunately all of these tests are nonspecific and blunted prolactin responses occur in patients with prolactinomas, hypothalamic tumors and in non-tumoral hyperprolactinemia.…”

Endocrinological differentiation of primary hypothalamic and pituitary disease

“…Only few studies have been performed along this vein and results sometimes conflicting have been reported 2, 33, 44, 50. In particular, some studies 44,50 have reported in patients after surgery appropriate PRL responses to TRH and metoclopramide and blunting of the PRL response to insulin hypoglycemia and chlorpromazine. Furthermore, according to some authors 5o but not others 4 the PRL responses to TRH and metoclopramide are reduced in the first months after surgery and return to normal later on.…”