PULSATILE GONADOTROPHIN SECRETION IN HYPERPROLACTINAEMIC AMENORRHOEA AND THE RESPONSE TO BROMOCRIPTINE THERAPY

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Abstract
Serum gonadotropin concentrations were measured every 15 min for 8 h in 6 patients before and at weekly intervals during initiation of bromocriptine treatment of hyperprolactinemic amenorrhea. Before treatment, mean gonadotropin levels were similar to those found in the normal follicular phase, but LH [luteinizing hormone] secretion was characterized by infrequent pulses of large amplitude. In 3 subjects the patterns of LH pulsatility and serum estradiol levels returned to normal within 7 days of starting bromocriptine. The other 3 subjects responded with an increase in the frequency of LH pulses and mean LH levels, but little rise in estradiol. Thus some hyperprolactinemic subjects have a defect in the ovarian response to endogenous gonadotropin stimulation, which may persist for a few weeks after return of prolactin levels to normal. The restoration of a normal rate of LH pulsatility with bromocriptine can occur without any change in serum estradiol concentration.