[Gonadotropin releasing hormone loading test with bromocryptin therapy: a new possibility in the differential diagnosis of normo-prolactinaemic anovulation].

An anovulation group with normal basal prolactin level (less than 600 mU/l) was found during GnRH loading tests. After GnRH administration there was a definite increase in prolactin value together with an insufficient hypophyseal response. Bromocriptine treatment was commenced on the 10th day (daily 2.5 mg) before carrying out the GnRH loading tests again. During the repeated tests prolactin levels remained normal, basal FSH and LH values increased and reactive hypophyseal responses occurred. On the basis of the examination a group ("latens hyperprolactinemia") responding with increased prolactin production during GnRH administration was found. This higher prolactin level inhibits gonadotropin release from hypophysis. In these cases ovulation induction with bromocriptine is adviseable in spite of basal prolactin level is normal.