FOLLICLE-STIMULATING HORMONE

LAB86

5 mL Gold SST

0.2 mL

7 mL Red Top Tube

Refrigerate

Set Up:Daily Report Available:1 day

Follicle-Stimulating Hormone

Female: Follicular: 3.5-12.5 mIU/mL Ovulation: 4.7-21.5 mIU/mL Luteal: 1.7-7.7 mIU/mL  Post-Menopausal: 25.8-134.8 mIU/mL Male: 1.5-12.4 mIU/mL

FSH and LH control growth and reproductive activities of the gonadal tissues. FSH promotes follicular development in the ovary and gametogenesis in the testis. The gonadotroph cells of the anterior pituitary secrete both FSH and LH in response to gonadotropin releasing hormone (LHRH or GnRH) from the medial basal hypothalamus. Both FSH and LH are secreted in a pulsatile manner, with rapid fluctuations over the normal range. The pulsatility of FSH is less pronounced than that of LH. Release of both FSH and LH from the pituitary is under negative feedback control by the gonads. FSH in mature females acts to stimulate development of the ovarian follicles. Circulating FSH levels vary throughout the menstrual cycle in response to estradiol and progesterone. A small, but significant increase in circulating FSH accompanies the mid-cycle LH surge. However, the physiological significance of this increase is unknown. Circulating levels of FSH decline in the luteal phase in response to estradiol and progesterone production by the developing corpus luteum. Because of the negative feedback mechanisms regulating gonadotropin release, elevated concentrations of LH and FSH are indicative of gonadal failure when accompanied by low concentrations of the gonadal steroids. In males, these observations suggest primary testicular failure or anorchia. FSH may also be elevated in Klinefelter's syndrome (seminiferous tubule dysgenesis) or as a consequence of Sertoli cell failure. In females, situations in which FSH is elevated and gonadal steroids are depressed include menopause, premature ovarian failure, and ovariectomy, while with polycystic ovarian syndrome the LH/FSH ratio may be increased. Abnormal FSH concentrations may also indicate dysfunction of the hypothalamic-pituitary axis. In sexually mature adults, FSH deficiency, together with low concentrations of LH and sex steroids, may indicate panhypopituitarism. This can result either from a decrease in the release of GnRH or from a lack of response of the pituitary to GnRH. Determination of serum FSH, following administration of GnRH may allow differentiation of these two conditions. The use of oral contraceptives usually results in reduction of gonadotropin levels due to negative feedback by these steroids.