LHRH 負荷試験による小児期のゴナドトロピン分泌予備能に関する検討ー高精度 LH, FSH 測定法 (IRMA 法) による分泌動態の解析ー

To investigate the age-related changes in the pituitary responsiveness to luteinizing hormone-releasing hormone (LH-RH), the consentrations of serum luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured before and after LH-RH administra-tion using the highly sensitive immunoradiometric assay (IRMA) in 283 normal children (161 males and 77 females) between 4 and 14 years old and in 22 patients (18 males and 4 females) with pituitary dwarfism. Then, the area of response above the basal level [integrated response(Σ)] of LH and FSH during 60 minutes after LH-RH injection was calculated to evaluate the pituitary response to LH-RH. The integrated LH responses progressively increased in the boys from 8 years of age and in the girls from 6 years of age, and they continued to increase up to 14 years of age. The integrated FSH response showed a significant decrease in all grups in the girls, but did not show any change in the boys. In patients with pituitary dwarfism who were subsequently found to be gonadotropin deficient, the level of Σ LH60 was low (below-2SD) It is concluded that integrated responses of gonadotropins, especially LH, to LH-RH are useful to evaluate the maturation of the hypothalamic-pituitary-gonadal axis, and that incre-ment of LH responsiveness to LH-RH already begins before the onset of puberty. The peak appearance time of gonadotropins after LH-RH is also important in the assessment of the maturation of the hypothalamic-pituitary-gonadal axis because FSH reached its peak carlier in the pubertal group than in the prepubertal group.