What is Follicle Stimulating Hormone Test (FSH test), and why is it done?

What is Follicle Stimulating Hormone (FSH)? 

The follicle-stimulating hormone or the FSH is a glycoprotein polypeptide hormone secreted by the gonadotropic cells of the anterior pituitary gland. The pituitary gland is present in the base of the human brain and is responsible for releasing many other hormones in the human body. The hormones act as messengers in the human body that guide the various organs to function smoothly and on time. The FSH is mainly responsible for the working of the reproductive system of humans.

The follicle-stimulating hormone or FSH is present in both female and male human beings. The basic functions of the follicle-stimulating hormone include the development, growth, pubertal maturity induction, and regulation of reproductive processes. In males, it is responsible for spermatogenesis or the production of sperm cells. In females, it works with the luteinizing hormone to induce the growth and development of egg cells in the ovary. The production of egg cells in the ovary is known as oogenesis.

The work of the follicle-stimulating hormone or FSH is to induce the oocytes or the primary cells present in the ovary to start growing into egg cells. It is the initial step before ovulation takes place. When the oocytes start maturing into eggs, they, in turn, start releasing estrogen, which is an indicator for the pituitary gland to stop producing the follicle-stimulating hormone or FSH.

Follicle Stimulating Hormone Test

When the levels of estrogen get higher, the production of the follicle-stimulating hormone gradually stops. Thus, follicle-stimulating hormone or FSH levels drop automatically as the eggs develop in the ovary. If the eggs do not mature and produce estrogen, the anterior pituitary keeps on producing the follicle-stimulating hormone in a bid to aid egg development.

What is the purpose of the Follicle Stimulating Hormone Test (FSH test)?

The purpose of the follicle-stimulating hormone test (FSH blood test) differs in men and women. In some cases, the test is also done on children.

FSH blood test for Women:

The test is done on women for the following reasons:

  • Assessing Infertility Problems: High FSH levels can indicate low ovarian reserve, which means that there are fewer eggs or the eggs may be of poor quality. This test can also be used to assess the potential effectiveness of in vitro fertilization, injectable fertility drugs, or treatments.
  • Assessing the irregularities in the menstrual cycle: FSH is responsible for inducing egg cells growth; if the ovulated egg is not fertilized, periods occur, and the production process of the egg starts all over again. If the menstrual cycle is abnormal, it is necessary to check whether the bloodstream has the mandatory level of follicle-stimulating hormone or FSH.
  • Diagnosis of abnormalities in the pituitary gland or disease in the ovaries: FSH levels are also monitored for problems with the pituitary gland or ovaries. If the amount of FSH in the bloodstream is higher or lower than the required amount, the pituitary gland may malfunction.

FSH blood test for Men:

The follicle-stimulating hormone test (FSH blood test) is done in males for the following reasons:

  • Evaluation of low sperm counts: Since the FSH is responsible for the process of spermatogenesis in men; the levels of FSH may be able to explain low sperm count.
  • To assess the occurrence of hypogonadism or gonadal failure: Hypogonadism or gonadal failure refers to the condition when the sex glands; in this case, the testes, produce very little testosterone. This leads to lower libido.
  • Assess the dysfunctionality of the testes.

FSH blood test for Children: 

The FSH blood test is useful to detect the early or late occurrence of puberty in a child. In the case of early puberty or precocious puberty, the child develops external and internal sexual features at a very early age, and in the case of late puberty, the child does not develop sexual features when they should.

When can the Follicle Stimulating Hormone Test or FSH test be conducted? 

The FSH test is usually conducted on the third day of the menstrual cycle or the third day of your period. Doctors allow the patients to take the test anytime between the second and fourth day of their period, but the third day gives the most accurate results. The timing is crucial in this case because the levels of FSH vary over the entire menstrual cycle, and for fertility testing or ovarian reserve testing, the third day of your period is said to give the most accurate results.

What is the procedure of an FSH test?

The FSH test is conducted like any other blood test by drawing blood from the veins. Sometimes, urine samples are also used to check the FSH levels.

What should be the normal FSH levels?

The FSH levels vary from person to person, depending on age, sex, and pre-existing medical conditions. However, there are some standardized normal levels.


  • 0 to 5.0 mIU/ml before puberty.
  • 0.3 to 10.0 mIU/ml during puberty.
  • 1.5 to 12.4 mIU/ml in adults.


  • 0 to 4.0 mIU/ml before puberty.
  • 0.3 to 10.0 mIU/ml during puberty.
  • 4.7 to 21.5 mIU/ml in menstruating women.
  • 25.8 to 134.8 mIU/mL in women after they stop menstruating; or in their menopause.

What are the alternatives for the FSH test?

The FSH test is the only way women can assess their fertility or check their ovarian reserves. The AMH (anti-Müllerian hormone) test can also be done to diagnose polycystic ovarian syndrome (PCOS) or to check ovarian reserves. The AMH test is said to provide better and more accurate results than the FSH test.

The AMH test can be taken any day of the menstrual cycle, which is an added bonus. The antral follicle counting ultrasound is another test that can be used to count the number of follicles of the same size to get an understanding of ovarian reserves.

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