Follicle Stimulating Hormone (FSH)

Follicle-stimulating hormone or FSH hormone testing is commonly done to check your reproductive potential. It is one of the two gonadotropic hormones (the other being luteinizing hormone) and is responsible for the development and function of ovaries in females and testes in males.

It is basically the hormone responsible for producing mature eggs in the ovaries. During IVF treatment, FSH is the hormone in those injectable gonadotropins that help produce multiple eggs for retrieval.

FSH is made in the pituitary gland and it plays an important role in the development and functioning of the sexual organs in both men and women. FSH levels in children remain low until they hit puberty, and then they begin to rise, indicating for the ovaries to make estrogen in girls and for the testes to make testosterone in boys.

Very high or very low levels of FSH means the puberty may arrive too early or too late.

FSH in women: regulates the growth of eggs in the ovaries and controls the menstrual cycle. The level of FSH in your blood changes throughout the menstrual cycle and is the highest right before ovulation.

FSH in men: regulates the production of sperm but unlike in women, the FSH levels in men do not change much.

FSH is also known as Follitropin.

What is the use of FSH test?

FSH test is usually done along with other hormone tests such as luteinizing hormone (LH), estradiol, testosterone, etc. usually to test your fertility and reproductive potential.

These tests are used differently for men, women, and children.

FSH test in women helps to:

• Diagnose the possible cause of infertility
• Find the reason for irregular or absent menstruation
• Predict the onset of menopause
• Check if the ovarian function is optimal

FSH test in men helps to:

• Find the reason for infertility
• Diagnose the reason for low sperm count
• Check for the optimal function of testicles

It is also used in both men and women to check for disorders of the pituitary or the hypothalamus glands, which may affect the production of FSH.

FSH test in children helps find the reason for premature puberty (before 9-10 years) or delayed puberty (after 13-14 years).

When should you do the FSH test?

The FSH test is recommended if you have:

• Conception problems: If you’re struggling to get pregnant even after 12 months of trying
• Irregular periods: If you have longer or shorter than normal periods and they are not regular every month
• Menopause: The FSH test can help to predict the possible onset of menopause in women
• Low sperm count: If a simple semen analysis shows reduced sperm count, your doctor may order the FSH test next
• Reduced sex drive: Unusually low sex drive or loss of muscle mass in men could be an indicator of underlying fertility problems
• Pituitary dysfunction: The FSH test may be also be recommended to check for pituitary dysfunction in any individual if they have the symptoms listed above, along with weakness, weight loss, fatigue, or reduced appetite
• Pubertal problems in children: FSH test is ordered in children when they do not seem to start showing the below signs of puberty or secondary sexual characteristics at the right age:
  • Pubic hair
  • Breast enlargement, beginning of menstruation in girls
  • Testicles and penis growth in boys

How does the FSH work?

The production of Follicle-stimulating hormone or FSH happens in the pituitary gland (located in the center of your head) but it is controlled by a complex system of the brain and hormones.

The hypothalamus in your brain first releases the gonadotropin-releasing hormone (GnRH), which indicates the pituitary gland to release the FSH and luteinizing hormone (LH). The FSH then signals the ovaries for growth and maturation of egg follicles.

The menstrual cycle has two phases: the follicular and the luteal, which last around 14 days each.

The maturation of eggs happens during the follicular phase, when FSH also initiates the production of estradiol in the ovarian follicle.

Estradiol and FSH then work together for further development these follicles. Towards the end of the follicular phase, when the FSH is highest (along with the LH), the ovaries are able to release an egg form the mature follicle.

Other hormones such as inhibin, progesterone, along with estradiol are responsible for regulating the amount of FSH released by the pituitary, which depends upon the ovarian response to the hormones.

With advancing age as the ovarian function gradually wanes, the levels of FSH and LH rise as they have to work harder to get the ovaries to release any egg. 

FSH in men is responsible for stimulating the testicles for the production of mature sperm cells and androgen binding proteins. FSH levels in men rise to a certain point during puberty and then remain stable through their lives.

Problems of hypothalamus, pituitary, the ovaries/testicles can mess the FSH levels in your body, which can result in delayed or early puberty, irregular menstrual cycles, or infertility.

What are normal FSH levels in Women?

Please note: The range of FSH levels varies with the lab doing your testing and the assay they are using. Ask your lab for the normal reference range for FSH by age and consult with your doctor, before making any interpretations.

Additionally, a comparison with your LH and estrogen levels (specifically estradiol, or E2) is required to get the entire picture.

What is the ideal FSH level for IVF?

Women with FSH levels under 10mIU/ml are expected to have a good response to ovarian stimulation and consequently, better chances of success in IVF.

If the level of FSH is between 10 and 15mIU/ml, the ovarian stimulation is relatively harder and more stimulation drugs may be required for successful egg retrieval.

FSH levels of 15-20mIU/ml indicates difficult ovarian stimulation and possibility of fewer eggs in the retrieval. The egg quality is these cases is also poor.

If the FSH is higher than 20 mIU/ml, stimulation may be very difficult and the chances of achieving a successful pregnancy are much lower. However, this does not mean you cannot get pregnant with your own eggs; it just means your doctor may need to try a different IVF protocol suited to your individual situation.

What is the normal FSH level by age?

Male:

Female:

FSH normal values are not the same for all laboratories as some of them use a different measurement standard or test different samples. Do not start to worry about your abnormal FSH test report without verifying with your doctor, what it means for you.

In what conditions is FSH level low?

If your FSH levels are abnormally low, it may indicate a dysfunction of the pituitary or hypothalamus.

In women, the other reasons for low FSH are:

• Significant loss of weight or being highly under-weight
• No ovulation (not producing any eggs)
• Pregnancy

Low FSH serum levels in women have also been associated with a higher risk of ovarian cancer.

Low FSH and LH levels in children may be a sign of delayed puberty, which may be caused by:

• Diseases of the ovaries/testes
• Hormone deficiency
• Eating disorders
• Genetic disorders like the Turner syndrome and Klinefelter syndrome
• Some infections

What are the reasons for high FSH levels?

High FSH levels, along with high LH in women is usually due to some damage to the ovaries due to auto-immune disease, chemo or radiotherapy. Other reasons include:

• Low ovarian reserve, premature-menopause or menopause
• Hormone therapy
• Turner syndrome, a chromosomal disorder that affects female sexual development and causes infertility.
• A tumor in the pituitary gland
• Other conditions that affect ovarian function such as PCOS, ovarian tumor, Thyroid problem, Adrenal diseases

High FSH levels in men may be due to:

• Testicular damage due to advanced age, alcohol, drugs, chemo or radiotherapy, viral infection (mumps)
• Hormone therapy
• Pituitary gland tumors
• Klinefelter syndrome, a genetic disorder that affects male sexual development.

High FSH levels in Children, when accompanied with high LH levels are an indicator of the start of puberty. It is typically expected at around 9 years girls or 10 years in boys (precocious puberty), it could indicate:

• An injury to the brain, or
• A disorder of the central nervous system

If you have received abnormal FSH results for your child, talk to your doctor immediately to see what’s going on.

It is important to note that FSH levels not only vary within a cycle, but can also be different in consecutive cycles. Having high or low FSH levels may not enough for your doctor to make a conclusive diagnosis.

While high FSH level is generally indicative of poor egg quality, having normal FSH report does not guarantee that your ovarian reserves are adequate. Despite normal FSH levels, your response to ovarian stimulation in IVF may be poor. Other hormone tests—LH, estradiol, testosterone, AMH—are done along with FSH for a better understanding of your fertility situation.

For more information about Follicle stimulating hormone (FSH) testing and to order your FSH test, get in touch using the red contact button on this page. *t&c apply.

Reviewd by: Dr. Meenakshi, PhD