FSH, the follicle stimulating hormone is present in both men and women. FSH is released by the anterior pituitary gland. In women, it stimulates production of eggs in the ovaries and thus, helps regulate menstruation. It also promotes development of placenta. In growing children, FSH levels determine the onset of puberty while in men, the hormone mainly governs the production of sperms. Thus, there exists a peculiar relationship between FSH levels and fertility in both men and women.
Normal FSH Levels in Men and Women
FSH test is carried out to find the exact cause of infertility in men and women. The test is also advised if a man does not have testicles, or has underdeveloped testicles. FSH levels vary, according to age and gender. In men, normal FSH levels are as described below.
- Before puberty : 0 - 5.0 mIU/ml (milli international units per milliliter)
- During puberty : 0.3 - 10.0 mIU/ml
- In adults : 1.5 - 12.4 mIU/ml
In women, normal FSH levels are as described below.
- Before puberty : 0 - 4.0 mIU/ml
- During puberty : 0.3 - 10.0 mIU/ml
- Menstruating women : 4.7 - 21.5 mIU/ml
- Postmenopausal women : 25.8 - 134.8 mIU/ml
Low FSH in Men
Low FSH levels in men are seen during hypopituitarism (affected pituitary function). In women, FSH levels keep on changing during the menstrual cycle but in men, they are more steady, as men produce sperms continuously. The FSH is produced by the anterior pituitary gland in response to the gonadotropin-releasing hormone (GnRH), released by the hypothalamus. In men, as FSH promotes testicular growth, low FSH levels can inhibit the growth of testicles.
High doses of testosterone during hormone therapy can affect the production of FSH in men. Maturation of spermatozoa is possible only with healthy FSH levels. Low FSH suggests that the man would not be able to produce sufficient sperms. Hypothalamus or pituitary problems can lower the output of FSH.
High FSH in Men
In men, high FSH levels suggest that the testicles are not working properly. The testicles might get damaged by some condition or trauma. High FSH levels indicate the presence of Klinefelter syndrome (presence of an extra X chromosome in a male), precocious puberty (premature sexual development in boys), multiple endocrine neoplasia (MEN) type I (more than one endocrine gland is overactive, often pancreas, parathyroid and pituitary become overactive and form a tumor, genetic disorder), testicle removal or male menopause.
The testicles produce a hormone called inhibin, which helps maintain normal FSH levels. Elevated FSH levels in men indicate that the testicles are not producing sufficient inhibin. This suggests testicular failure which can be partial or complete. In women, high FSH levels indicate menopause.
To find out the causes of infertility, follicle stimulating hormone levels are first checked by ordering a blood test. Release of sperms can be affected due to several reasons. Very high FSH levels with normal levels of other hormones suggest that there is some problem in the initial sperm production while low levels of inhibin indicates that there can be blockage, or some structural defect, in the seminiferous tubules. Sperm production gets affected in the initial stage if the testicles are severely defective. Sertoli cell-only syndrome is the condition wherein sperm-manufacturing cells are absent.
Treatment for elevated or low FSH levels depends upon the cause of abnormal FSH levels. A simple blood test helps measure FSH levels. FSH level above 15 mIU/ml in a man is considered as very high. Low FSH levels usually indicate improper development or underdevelopment of the sexual organs. They suggest that the body is not functioning well. Abnormal FSH levels not only lead to low sperm count and infertility, but they also lead to other illnesses like eating disorders, multiple disorders of gonadotropin hormone, etc. Hormonal imbalance in men and women can result in several health complications.