Prolactin secretion in girls with isolated gonadotrophin deficiency.

Plasma prolactin, basal levels and the response to an i.v. injection of TRH (100 microgram/m2) was determined in five girls with isolated gonadotrophin deficiency of hypothalamic origin before and after at least 3 months cyclic replacement therapy with conjugated oestrogens (1.25 mg/day). The basal plasma prolactin levels were similar during both tests, however, during oestrogen therapy the mean peak response to TRH almost doubled and the sum of all the values obtained (basal, +15, +30 and +60 min) was significantly higher. It is of note that even upon prolonged oestrogen deprivation the releasable prolactin response to TRH was adequate.