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.