Disappearance Rates of Endogenous Follicle-Stimulating Hormone in Serum Following Surgical Hypophysectomy in Man

The disappearance rates of endogenous FSH in serum following complete hypophysectomy were determined in 5 patients. Simultaneous determinations of serum FSH and LH were made in one patient. The hormone concentrations were measured by specific radioimmunoassays. Endogenous FSH disappears from circulation at a much slower rate than endogenous LH (approximately 10-fold). The disappearance rates for FSH, like that of LH, could be resolved into at least 2 exponential components. The initial fast component has a mean t½ of 3.9 hr, which was followed by a second slow component with a mean t½ of 70.4 hr.