HYPOGONADISM, GALACTORRHOEA AND HYPER-PROLACTINAEMIA: EVALUATION OF PITUITARY GONADOTROPHINS RESERVE BEFORE AND UNDER BROMOCRIPTINE

Twenty patients with hypogonadism (19 women with amenorrhoea and 1 man with impotence and infertility), galactorrhoea and hyper-prolactinaemia (range: 36 to 344 ng/ml) were studied. The radiological study of the sella turcica, including in all cases hypocycloidal tomograms, allowed classification of the patients into 3 groups: group I (n = 4) had a grossly enlarged sella turcica, group II (n = 12) had localized alterations indicating the probable existence of a prolactin-secreting microadenoma ("microdeformation") while group III patients presented no radiological abnormality. Before treatment, all the patients were submitted to a complete evaluation of the function of their anterior pituitary, including the LH and FSH responses to iv administration of Gn-RH. All the group I patients had low basal LH levels and a blunted response to Gn-RH. The basal LH and in response to Gn-RH were normal in most of the group II patients and in all of the group III patients. An exaggerated FSH response to Gn-RH was observed in 6/12 patients with microdeformation (group II) but not in groups I and III patients. A low LH and a blunted LH response to Gn-RH is highly suggestive of the existence of a pituitary prolactin-secreting adenoma in case of amenorrhoea and hyper-prolactinaemia patients; a normal response does not however rule out such a diagnosis. The reasons for a exaggerated FSH response to Gn-RH in patients with suspected prolactin-secreting microadenoma remain to be investigated though this pattern can also occur in other cases of amenorrhoea. Hence the Gn-RH test might contribute to the assessment of the hypothalamo-pituitary axis of patients with hyper-prolactinaemia. Six patients treated for 4 months with bromocriptine (CB-154) were submitted to re-evaluation of their pituitary gonadotrophins reserve. All the women experienced restoration of menses with 39 days of treatment and the male patient regained potency. It was observed that bromocriptine treatment and subsequent normalized prolactin levels in the 4 group II women tested were associated with normalization of their previously exaggerated FSH response to Gn-RH; LH responses were also diminished in these cases. These data are compatible with the hypothesis that hyper-prolactinaemia per se could interfere with the endogenous secretion of Gn-RH at the hypothalamic level. In one patient with grossly enlarged sella turcica and a previous lack of an LH and FSH response to Gn-RH, bromocriptine treatment restored a normal gonadotrophins response, confirming that, in this case, the alteration of this response was indeed due to a prolonged lack of endogenous Gn-RH secretion.Gonadotropin levels in basal conditions and after gonadotropin-releasing hormone (Gn-RH) stimulation in 20 patients with hypogonadism, galactorrhea, and hyperprolactinemia are reported and, in some cases, results after treatment with bromocriptine are included. The radiological study of the sella turcica allowed classification of the patients in 3 groups: 1) grossly enlarged sella turcica, 2) localized alterations indicating the probable existence of a prolactin-secreting microadenoma, and 3) no radiological abnormality. All the Group 1 patients had low basal luteinizing hormone (LH) levels and a blunted response to Gn-RH. Basal LH and the response to Gn-RH were normal in most of Group 2 and in all of Group 3. An exaggerated follicle stimulating hormone (FSH) response to Gn-RH was observed in 6 of 12 patients in Group 2 but not in the other groups. It is suggested that the Gn-RH test might contribute to the assessment of the hypothalamo-pituitary axis of patients with hyperprolactinemia. 6 patients teated for 4 months with bromocriptine experienced restoration of menses or regained potency. These results are compatible with the hypothesis that hyperprolactinemia per se could interfere with the endogenous secretion of Gn-RH at the hypothalamic level.