THE PATTERN OF GONADOTROPIN AND ESTRADIOL SECRETION IN EXAGGERATED THELARCHE

Purpose: To assess the dynamics of the pituitary-ovarian axis in exaggerated thelarche, defined as premature thelarche associated with signs of systemic estrogen effects (advanced bone age and/or growth acceleration) without progression to complete puberty. Subjects and methods: Seven girls (age < 2.5 years) with exaggerated thelarche, 6 girls with inactive pituitary-ovarian axis (premature adrenarche) and 21 girts with activated axis (central precocious puberty) had serum FSH, LH and E2 measured serially before and 1 to 24 h after gonadotropin-releasing hormone agonist (GnRHa) administration (leuprolide, 20 mug/kg sc). used as a test of combined pituitary-ovarian stimulation. Results: Although girls in the exaggerated thelarche and adrenarche group had similar [mean (SEM)] baseline FSH [3.2 (0.9) vs 1.4 (0.3) IU/11, LH [0.36 (0.1) vs 0.27 (0.02) IU/1] and E2 [20 (1.2) vs 21 (2) pmol/l] concentrations, and similar peak post-GnRHa LH concentrations [5.5 (1.1) vs 2.4 (0.5) IU/l], girls with exaggerated thelarche achieved higher peak FSH [41 (9) vs 14 (3) IU/1, p < 0.01] and E2 [243 (40) vs 37 (6) pmol/l, p < 0.001] concentrations after GnRHa. In comparison to patients with exaggerated thelarche, girls with precocious puberty had higher (p < 0.01-0.001) baseline LH [3.6 (0.8) IU/l], baseline E2 [69 (11) pmol/1], GnRHa-stimulated peak LH [68 (17) IU/l] and peak E2 [648 (58) pmol/l] concentrations, but similar FSH parameters. Conclusions: Girls with exaggerated thelarche exhibit substantial E2 Secretory potential that can be demonstrated by GnRHa stimulation, is predominantly FSH-driven, and probably accounts for the manifestations of estrogen effect seen in these girls.