Summary

This test measures the level of follicle stimulating hormone (FSH) in your blood. FSH is made in the pituitary gland and plays an important role in sexual development and function. The test is used to assess fertility and pituitary disorders in men and women. 

In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. Its level varies throughout the menstrual cycle and is highest just before ovulation when an egg is released. This is known as ovulation. FSH testing is used to investigate irregular menstrual periods or confirm menopause. 

In men, FSH stimulates testicular growth and helps create and maintain normal sperm count. The test is used to find out if there is a problem with the testicles or what may be the cause of a low sperm count. It is also often used to investigate early or delayed puberty.

Why get tested?

FSH is part of a complex system involving several hormones that together control sexual development and function.  It works closely together with luteinising hormone (LH).

_{Figure 1: The hypothalamus region of the brain produces gonadotrophin-releasing hormone (GnRH) which acts on the testes (left) and on the ovary (right).}

The GnRH affects the pituitary gland, which sits just at the base of the brain, causing it to produce follicle stimulating hormone (FSH) and luteinising hormone (LH).

Women

_{Figure 2: Hormonal fluctuations during the menstrual cycle} 

Day 0 is the first day of menstruation. FSH stimulates the growth of eggs in the ovaries during the first half of the menstrual cycle (follicular phase). It does this by causing the egg follicle to produce oestradiol. At about mid-cycle there is a surge of FSH and LH which is followed by ovulation - the release of the egg from the lead follicle at about day 14.  The fertile period begins about five days before the LH surge and ends the following day as the egg quickly degenerates if not fertilised. 

During the second half of the menstrual cycle (luteal phase) FSH stimulates the production of progesterone.

Menstrual cycle times can vary widely between people. This makes it difficult to calculate the exact timing of the fertile period. As a woman ages and menopause approaches, ovarian function wanes and eventually stops and as this occurs, the levels of both FSH and LH rise.

Men

In men, FSH stimulates the testicles to produce sperm. Normally, FSH levels do not change much throughout the course of a man’s life. LH is measured to investigate the cause of low testosterone.

Children

In children, FSH levels rise soon after birth and then fall to very low levels in infancy.  They remain low until puberty when levels begin to rise again. In girls, this stimulates the ovaries to make oestrogen. In boys, it stimulates the testicles to make testosterone.

Disorders affecting the hypothalamus, pituitary, and/or the ovaries or testicles can cause too much or too little FSH to be made. This can result in conditions such as infertility, abnormal menstrual cycles, or early or delayed puberty.

Measuring FSH

Follicle stimulating hormone (FSH) is often used in conjunction with other tests including LH, testosterone, oestradiol and progesterone. They are used to investigate:

• infertility 
• low sperm count
• irregular periods 
• pituitary gland disorders
• menopause 
• delayed or early puberty.

Having the test

Sample

Blood

Any preparation?

None

Your results

Reading your test report

Your results will be presented along with those of your other tests on the same form.  You will see separate columns or lines for each of these tests.  

The results of an FSH test are usually considered along with those of other hormone tests.

Women

FSH and LH levels can help show whether there is a problem with the ovaries or whether there is a disorder of either the pituitary gland or the hypothalamus.

Increased levels of FSH and LH are consistent with a problem with the ovaries. 

Low levels of FSH and LH suggest a pituitary or hypothalamic problem.

When a woman enters the menopause her ovaries stop working and FSH levels rise.

Men

High FSH levels are due to a problem with the testicles. This can be due to developmental issues or an injury to the testicles.

Low levels of FSH suggest pituitary or hypothalamic disorders.

Children

Higher levels of FSH and LH than expected for age along with the development of secondary sexual characteristics such as pubic hair and breasts at an unusually young age are an indication of early puberty. This is much more common in girls than in boys.

In delayed puberty, LH and FSH levels can be normal or below what is expected for a person within their age range.

Reference intervals

Your results will be compared to reference intervals (sometimes called a normal range).

• Reference intervals are the range of results expected in healthy people. 
• When compared against them your results may be flagged high or low if they sit outside this range.
• Many reference intervals vary between labs so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms.   It is important that you tell them everything you think might help. 

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely. 

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

Any more to know?

FSH levels can be higher with the use of some drugs including cimetidine, clomiphene, and naloxone. FSH results can be falsely elevated in people who are taking large doses of biotin as this can interfere with the test method. FSH levels can be lower with oral contraceptives, phenothiazines and hormone treatments. 

More information

Pathology and diagnostic imaging reports can be added to your My Health Record. You and your healthcare provider can now access your results whenever and wherever needed.

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