The roles of various circulating forms of FS and inhibin in the regulation of FSH secretion have yet to be elucidated during pubertal maturation. We determined serum levels of total FS and dimeric inhibin A and B in 6 boys and 7 girls with CPP prior to GnRHa therapy (PRE); after 1 year of pituitary-gonadal suppression (ON), and 1 year following reactivation of puberty (OFF) (mean ± SEM). Serum levels of FS and inhibin A did not change significantly in either sex, with all concentrations of the latter close to assay sensitivity save for a single determination in a female OFF therapy. Inhibin B levels declined significantly during GnRHa suppression and were higher in males than females prior to and during therapy.Conclusions: Inhibin B appears to be the predominant form of circulating inhibin during puberty with sex differences that may relate to sexual dimorphism of FSH regulation. Supported by HD-18169, U54-29164, P30-28138, and RR-1066. Table

Table 1
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