CIRCULATING LEVELS OF FOLLISTATIN FROM PUBERTY TO MENOPAUSE

Objective: To determine the changes in circulating levels of follistat in, a binding protein for activin and inhibin, through the reproductiv e life cycle in women. Design: An open, prospective descriptive study. Setting: An academic endocrine research unit. Patients: Prepubertal ( n = 10), midpubertal(n = 7), and postpubertal (n = 25) (early adolesce nt) girls, normal cycling adult women (n = 8), postmenopausal women (n = 17), and men (n = 13) were studied. Interventions: Normal cycling w omen were given Nal-Glu GnRH antagonist for 3 days in the follicular p hase of the cycle. Main Outcome Measure: Serum concentrations of folli statin determined in a heterologous RIA. Results: Mean follistatin lev els did not change during puberty but were higher in adult and postmen opausal women. Levels of immunoreactive follistatin in men were lower than levels found in normal cycling women and postmenopausal women. Da ily immunoreactive follistatin levels during the menstrual cycle remai ned constant and did not change significantly after ovarian suppressio n with GnRH antagonist. Conclusion: Because dynamic changes of serum i mmunoreactive follistatin do not occur during ovarian activation (pube rty), suppression, and age-related ovarian failure, the increase in im munoreactive follistatin levels in adult and postmenopausal women may implicate sources of follistatin other than the ovary.