Follicle Stimulating Hormone (FSH)

July 21, 2020

What is FSH?

Follicle stimulating hormone (FSH) is a hormone made by the pituitary gland in the brain.[1] Both men and women produce FSH but it has slightly different functions in each gender. It is a hormone which is essential for our development during puberty and is associated with the function of the ovaries in females and the testes in men.[2]

The production of FSH is a multifaceted approach involving other hormones made by the hypothalamus (gonadotrophin-releasing hormone -GnRH), pituitary glands, ovaries and testes. This is why the control of producing FSH is so complex.

Why take a FSH blood test?

In females, FSH levels along with luteinising hormone (LH) levels can distinguish between primary and secondary ovarian failure. If levels of FSH and LH are increased then this is indicative of primary ovarian failure due to reduced responsiveness of the ovaries. Whereas low FSH and LH alongside low oestrogen levels show secondary ovarian failure due to down regulation of hypothalamic-pituitary axis.

Increased FSH levels will rise when a woman enters the menopause because her ovaries will no longer work. In men, high levels of FSH are a result of testicular failure and confirm there is little or no sperm production.

It is important your FSH levels are measured at the correct time during your cycle. FSH levels fluctuate during your menstrual cycle and your sample should be taken within the first four days to enable comparison to appropriate reference range for that phase of the cycle. If you are going through the menopause, on the other hand, your sample can be taken at any time.

You can test your FSH levels along with other key fertility hormones by purchasing a simple at-home finger prick test kit which is then analysed at an accredited lab. Forth offers a number of blood tests which include FSH such as Female FertilityMale HormonesPerimenopause & Menopause Health

What function does FSH have in the body?

FSH has regulatory functions in the reproductive systems of both males and females.

In females, FSH is an important hormone in the menstrual cycle because it promotes the growth and development of ovarian follicles during the follicular phase of the cycle. Ovarian follicles are fluid-filled sacs which contain immature eggs, during ovulation a mature egg is released from an ovarian follicle. As the follicles mature, a dominant follicle eventually takes over and releases oestradiol and inhibin, suppressing the secretion of FSH.

The levels of FSH peak just before the surge in luteinising hormone which causes ovulation. During the next stage of the menstrual cycle, known as the luteal phase, FSH levels are reduced to prevent the development of new follicles.[3] However, during this phase, LH controls the production of progesterone from the corpus luteum. Oestrogen and progesterone help the pituitary gland control the amount of FSH is produced.

In men, FSH production is controlled by circulating levels of testosterone and inhibin, both of which are produced by the testes. Testosterone is regulated by FSH. Therefore, when testosterone levels increase nerve cells in the hypothalamus detect the rise so GnRH and FSH production can be reduced. When testosterone levels fall, the opposite happens, this is known as a negative feedback loop. As a result, testosterone production is maintained at a steady rate. Inhibin is controlled in a similar way but changes are detected by the pituitary gland rather than the hypothalamus. Increased FSH levels are associated with a reduction in sperm production, usually occurring with low inhibin levels. This is due to a disturbed feedback loop between the hypothalamus, pituitary gland and testes.[4]

How do changes in FSH affect health and wellbeing?

Because high levels of FSH are associated with reduced responsiveness of the ovaries or testes, the effects can interfere with your everyday life, particularly as it may hinder your chances of having a baby. Increased levels of FSH are associated with primary ovarian failure or testicular failure. Infertility is responsible for many psychological and social issues for both couples and individuals. As a result, failure to conceive has been associated with reduced sexual intimacy, depression and stress. [5]

In women, FSH levels rise naturally around the time of the menopause, highlighting the reduced function of the ovaries as well as the reduction in oestrogen and progesterone production. The menopause can negatively affect wellbeing because of both the psychological and physical symptoms during the transition.[6]

If you are worried about your FSH level or just want to check where you fall on the range, you can test your level with a simple at-home blood test.

​What can cause FSH to change?

Changes in FSH levels may be caused by an imbalance in the pituitary gland or the hypothalamus. Equally, individuals who have had eating disorders like anorexia and bulimia tend to have reduced FSH levels.[7]

A common reason for increased levels of FSH in females is the menopause. FSH is released to cause ovulation by maturing ovarian follicles. However, during the menopause, the ovaries stop working and no longer produce follicles. Usually, once a follicle matures and releases an egg, a structure called the corpus luteum forms which produces progesterone and suppresses the release of FSH. However, because there are no follicles and subsequently no corpus luteum, FSH levels continue to rise.[8]


What are the most common symptoms?

The menopause causes differing levels of hormones in the system, which are responsible for various side effects, including:

  • Hot flushes
  • Mood changes
  • Night Sweats
  • Difficulty sleeping
  • Headaches
  • Stiff joints
  • Urinary tract infections (UTIs)[9]

Primary ovarian failure can present with similar symptoms to the menopause. It is most commonly associated with:

  • Periods stopping
  • Irregular periods
  • Hot flushes[10]

How to keep FSH in the healthy range

Making improvements to your lifestyle can help to reduce the symptoms associated with increased FSH levels or may help with your fertility. A key factor in reproductive issues is obesity. Therefore, it is important to stay within a healthy weight range.

When menstruating, it is essential women keep their iron levels adequate to deal with the blood loss.  Foods which are good sources of iron include:

  • green leafy vegetables
  • red meat
  • liver

You should aim to eat a healthy, balanced diet which incorporates essential fatty acids to help increase hormone levels.

Exercise is also important. Controlled weight loss in overweight individuals has been shown to help restore reproductive function. Exercise is also great for psychological issues too, like depression and mood changes which have been linked to the menopause.

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[1] Lab Tests Online. (2015). FSH Test. Available at:

[2] You and Your Hormones. (2018). Available at:

[3] Orlowski, M and Sarao, M, S. (2018). Physiology, Follicle Stimulating Hormone. In: StatPearls [Internet].

[4] Schubert, M., Pérez, L and Jӧrg Gromoll. (2019). Pharmacogenetics of FSH Action in the Male. Frontiers in Endocrinology: 10(47).

[5] Baghianimoghadam, M, H., Aminian, A, H and Fallahzadeh, H. (2013). Mental Health Status of Infertile Couples Based on Treatment Outcome. Iranian Journal of Reproductive Medicine: 11(6), pp 503-510.

[6] Brown, L., Bryant, C and Judd, F, K. (2014). Positive Well-Being During the Menopausal Transition: A Systematic Review. Climacteric: 18(4).

[7] Resch, M. (2004). Eating Disorders from a Gynaecologic and Endocrinologic View: Hormonal Changes. Fertility and Sterility: 81(4), pp 1151-1153.

[8] Mason, A, S. (1976). The Menopause: The Events of the Menopause. R Soc Health J: 95(2), pp 70-71.

[9] NHS Choices. (2015). Menopause. Available at:

[10] Maclaran, K and Panay, N. (2010). Premature Ovarian Failure. J Fam Plann Reprod Health Care: 37, pp 35-42.

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This information has been medically reviewed by Dr Nicky Keay

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas' Hospital.

Dr Nicky Keay

Dr Nicky Keay

BA, MA (Cantab), MB, BChir, MRCP.