Follicle stimulating hormone is a hormone which is produced by the pituitary gland in the brain. FSH is present in both men and women and has slightly different functions. The production of FSH is controlled by a multifaceted feedback system which includes other hormones produced by the ovaries or testes and parts of the brain (pituitary gland and hypothalamus).
Follicle stimulating hormone regulates the functions of the reproductive system in both males and females.
In men, FSH is released in response to gonadotrophin-releasing hormone (GnRH) from the hypothalamus. It is widely considered as the hormone of puberty as an increase in FSH prompts testicular growth and the production of sperm.
In women, FSH plays a role in the menstrual cycle. It promotes the growth and development of the unfertilised eggs, also known as ovarian follicles during the proliferative or follicular phase of the menstrual cycle. At the start of the menstrual cycle, FSH stimulates the growth of ovarian cells in the developing egg to produce another sex hormone called oestradiol. During the follicular phase of the menstrual cycle, the levels of oestradiol rise and are at their highest just before ovulation happens mid-cycle. Between 24 and 36 hours after this peak in oestradiol, another hormone called luteinizing hormone (LH) increases. LH is essential for ovulation. During the next phase of the menstrual cycle – luteal phase – FSH is associated with the stimulation of progesterone, a hormone which helps the female body prepare for pregnancy. The control of FSH production by the pituitary gland is helped by the two hormones, oestradiol and progesterone. During the menopause FSH levels increase due to the ovaries not working anymore. While during pregnancy FSH is undetectable because oestrogen levels increase.
High and low levels of FSH can signify different medical conditions in both men and women.
High levels of FSH alongside LH can be a sign of primary ovarian failure and can be caused by developmental defects or disease. During the menopause women also have high levels of FSH in their system and this is a normal response. Due to the changing levels of hormones in your system, the menopause can cause several side effects, including:
In men, high levels of FSH can be a sign of primary testicular failure and can represent low or no sperm production.
Low levels of FSH and LH can represent an imbalance in the pituitary gland or hypothalamus. Individuals who have had eating disorders such as anorexia and bulimia tend to have low FSH levels.
Both low and high levels of FSH can have consequences for fertility. In men, high FSH could suggest testicular failure. Low levels, on the other hand, could suggest hypogonadism – reduced hormone secretion or other physiological activity of the testes.
The use of exogenous drugs based on testosterone or oestrogen can effect levels of FSH.
Infertility can present several psychological and social problems for couples and individuals. It can cause stress on the relationship, decrease sexual intimacy and cause depression. Low levels are also seen in pregnancy.
If you are female, it is important that your FSH levels are determined at the right time during your menstrual cycle. During your cycle, FSH levels will fluctuate and so the sample should be taken within the first four days of your cycle to give an accurate result. If you are going through the menopause then your sample can be taken at any time. Taking steps to improve your lifestyle may help to reduce the symptoms associated with your FSH levels or help improve your fertility status. Obesity can have a role in many reproductive disorders. Other lifestyle factors which should be addressed include smoking, alcohol intake and stressors.
During menstruation it is important to keep your body fuelled up on iron so include sources such as dark green leafy vegetables, red meat and liver.
In general, you should aim to eat a balanced diet. Increasing your essential fatty acids (EFA’s), like those found in oily fish, can help to increase hormone levels.
Controlled weight loss has been shown help restore reproductive function. Exercise should be encouraged, and you should aim to complete around 150 minutes of exercise per week spread over a few days.
Over exercise can have a negative impact due to energy deficiency.
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 Lab Tests Online UK. (2015). FSH Test. Available at: https://labtestsonline.org.uk/tests/fsh-test
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 Wira, C, R., Rodriguez-Garcia, M and Patel, M, V. (2015). The Role of Sex Hormones in Immune Protection of the Female Reproductive Tract. Nature Reviews: Immunology: 15(4), pp 217-230.
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