Pituitary function in a man with congenital aromatase deficiency: effect of different doses of transdermal estradiol on basal and stimulated pituitary hormones

To clarify the role of estrogen on male pituitary function, the effects of different doses of transdermal E2 on pituitary secretion were evaluated in a man with aromatase deficiency. The study protocol was divided into the following three phases: no E2 treatment (phase 1); 25 mug transdermal E2 twice weekly for 9 months (phase 2);12.5 mug transdermal E2 twice weekly for 9 months (phase 3). Pituitary function was studied in detail during each phase of the study protocol by measuring hormone levels in basal conditions and after dynamic testing (GnRH, insulin tolerance test, GHRH plus arginine, TRH, and corticotropin-releasing factor; tests). Basal and GnRH-stimulated gonadotropin levels resulted inversely related to E2 serum levels, according to the dosage of estrogen administered. Basal and stimulated GH, PRL, and TSH serum levels did not change during the protocol study. The secretory pituitary reserve of GH was clearly impaired. Basal and stimulated ACTH and cortisol serum levels were not modified by estrogen administration. This study demonstrated that in the human male E2 is required at pituitary level for normal functioning of gonadotropin feedback both in basal and stimulated conditions. In this patient GH deficiency seems to be an adult-onset event since he reached a tall stature. However, the finding of a severe impairment in GH response to potent provocative stimuli together with the insensitivity of GH/IGF-I axis to circulating estrogens strongly suggest a possible involvement of estrogens on both the development and maturation of the somatotrophic axis. Finally, the congenital lack of estrogen activity seems to be associated with a slightly impaired secretion of PRL and TSH, suggesting a possible role of estrogens on the pituitary secretion of these hormones in the human male