Responsivity of Pituitary Gonadotropes to Luteinizing Hormone-releasing Factor in Idiopathic Precocious Puberty, Precocious Thelarche, Precocious Adrenarche, and in Patients Treated with Medroxyprogesterone Acetate

Abstract

Extract: One hundred micrograms synthetic luteinizing hormone-releasing factor (LRF) were administered to 13 girls and 2 boys with idiopathic precocious puberty, 3 girls with precocious thelarche, 2 girls with precocious adrenarche, and 5 children treated with medroxyprogesterone acetate (MPA). Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex steroid responses were assessed. The mean readily releasable LH rose to a peak of 8.4 ± 1.8 ng/ml (LER 960) in the children with idiopathic precocious puberty and was significantly greater than in normal prepubertal (1.8 ± 0.14) or pubertal children (4.9 ± 0.34). The peak plasma FSH response (8.4 ± 1.4 ng/ml) (LER 869) was higher in precocious puberty but not significantly greater than in normal prepubertal (5.3 ± 1.9) or pubertal girls (6.0 ± 1.2). The mean concentration of plasma estradiol rose significantly above resting levels after LRF in the girls with idiopathic precocious puberty. The LH response in girls with precocious thelarche and adrenarche was in the prepubertal range. In 4 of 5 children with sexual precocity treated with MPA, the LH release evoked by LRF was diminished. Speculation: Premature neural activation of hypothalamic LRF synthesis and release may occur in children with idiopathic precocious puberty. This leads to increased pituitary gonadotropin synthesis, storage, and more readily releasable LH. The higher FSH release after LRF in normal girls than boys may be a factor in the strikingly higher prevalence of idiopathic precocious puberty in girls than in boys.