ONTOGENY OF GONADOTROPIN AND INHIBIN SECRETION IN NORMAL GIRLS THROUGH PUBERTY BASED ON OVERNIGHT SERIAL SAMPLING AND A COMPARISON WITH NORMAL BOYS

We measured luteinizing hormone (LH) and follicle stimulating hormone (FSH) by immunofluorometric assays and alpha-inhibin by radioimmunoass ay in serum sampled every 10 min throughout the night (2100-0500 h) fr om 44 normal girls. Mean overnight LH values rose log-linearly from a mean of 0.2 IU/l in prepubertal girls to 3.0 IU/l in late pubertal gir ls. Log(2) mean overnight FSH rose rapidly through early puberty and t hen remained, constant; mean FSH rose from 1.0 IU/l in prepubertal gir ls to -2.8 IU/l in Tanner III-V girls. Mean overnight inhibin increase d through puberty, rising from 151 ng/l in prepubertal girls to 432 ng /l in fully pubescent girls. Within each of the first three Tanner sta ges, LH differed similar to 100-fold between the smallest and largest mean concentrations but differed <10-fold within stages IV or V. Such within-pubertal stage variability was less pronounced for FSH, which d iffered similar to 16-fold among Tanner I subjects and 4-10-fold at la ter stages, and for inhibin, which varied similar to 4-fold within eac h Tanner stage. The frequency of LH pulses during overnight sampling i ncreased significantly during puberty, but the frequency of FSH and in hibin pulses remained constant. We compared the results from girls to those from 50 normal boys [Manasco et al. (1995) J. Clin, Endocrinol. Metab., SO, 2046-2052]. At each pubertal stage, girls had approximatel y the same mean overnight LH values as boys; girls had higher mean ove rnight FSH, particularly during Tanner stages II-IV; and boys had mean overnight alpha-inhibin immunoreactivity similar to 1.5 times that of girls at each pubertal stage. Still, hormone concentrations for indiv iduals of both sexes intergraded at each pubertal stage.