IMPAIRED LUTEINIZING-HORMONE RESPONSIVENESS TO GONADOTROPIN-RELEASING-HORMONE IN THE INFERIOR PETROSAL SINUSES OF HYPERPROLACTINEMIC PATIENTS

The aim of this study was to evaluate serum baseline and gonadotropin- releasing hormone (GnRH)-stimulated follicle-stimulating hormone (FSH) and luteinizing hormone (LH) concentrations in the inferior petrosal sinuses and in peripheral blood in nine normoprolactinemic and eight h yperprolactinemic patients who were being subjected to perihypophyseal phlebography for diagnostic purposes or neurosurgical indications. Se rum FSH and LH concentrations were significantly higher in both inferi or petrosal sinuses than in peripheral blood (p < 0.001 and p < 0.05, respectively) in normoprolactinemic but not in hyperprolactinemic pati ents. Additionally, in normoprolactinemic patients, the LH response to intravenous bolus GnRH in the inferior petrosal sinuses (evaluated as peak/basal) was significantly greater than in hyperprolactinemic pati ents (p < 0.01). No difference was found as far as FSH response to GnR H was concerned. In conclusion, these findings suggest that the hypogo nadism of hyperprolactinemic patients may depend on the impaired relea se of LH at the pituitary level.