[Delayed puberty and hypogonadotrophic hypogonadism: differential diagnosis with prolactin stimulation probe with...

We studied the changes in plasma levels of prolactin after an intramuscular injection of 0.33 mg/kg chlorpromazine and changes in plasma levels of LH and FSH after the injection of 100 micrograms iv GnRH, in 16 patients with delayed puberty, 10 patients with hypogonadotrophic hypogonadism and 6 healthy controls. Prolactin response was significantly lower in patients with hypogonadotrophic hypogonadism compared to subjects with constitutional delayed and healthy controls (delta Prolactin 7.05 +/- 1.7, 28.9 +/- 2.7 and 22.0 +/- 3.4 ng/ml respectively). LH response to GnRH was also lower in patients with hypogonadotrophic hypogonadism, compared to the other two groups (delta LH 4.3 +/- 2.5, 13.4 +/- 5.4 and 17.2 +/- 4.8 mUI/ml respectively) however, there was a great overlapping of values. No differences between groups were observed in responses of FSH, testosterone and estrogens to GnRH. It is concluded that prolactin response to chlorpromazine is useful in the differential diagnosis of constitutional delayed puberty.