FSH

Follicle Stimulating Hormone. A hormone involved in sperm production and in development of follicles (fluid filled parcels in the ovaries which contain the eggs).

Follicle-stimulating hormone (FSH) is a hormone made by the pituitary gland. This is a small gland located underneath the brain, which influences nearly every part of the human body. The production of FSH from this gland helps to control sexual development and functioning in both male and female bodies, in different ways:

  • In female bodies, FSH helps to control the menstrual cycle and stimulates the growth of eggs in the ovaries. FSH levels change in women, or in non-binary or transgender patients who were born female, throughout their menstrual cycle. The highest levels of the hormone will be recorded just before an egg is released
  • In male bodies, FSH helps to control the production of sperm. In most cases, the levels of FSH in men, or in non-binary or transgender patients who were born male, will not change very much
  • In children, levels of FSH will usually be low until they reach puberty. At this point, the levels will begin to rise to signal to female children that their ovaries should produce oestrogen, while in male children it signals to the testes to make testosterone


Follicle stimulating hormone, 3D illustration

 

There may be several different issues caused by having too little or too much FSH. These include infertility, menstrual difficulties in female patients, low sex drive in male patients, or early or delayed puberty in children. 

Specialists can carry out an FSH test to determine the levels of FSH in your blood. This will often be carried out alongside a test to test levels of luteinizing hormone (LH) present, as both work together to control sexual functions. These tests are carried out for different reasons, depending on whether the patient is an adult male, an adult female, or a child.

For female patients, an FSH test may be used to:

  • Help find out the cause of infertility issues
  • Determine if there is a problem with ovarian function
  • Help find out the reasons for irregular or stopped periods
  • Confirm the start of the menopause, or perimenopause (the transition period before menopause)

For male patients, an FSH test may be used to:

  • Help find out the cause of issues with infertility
  • Find out the reason for a low sperm count
  • Find out if there is a problem with the testicles

For patients who are children, FSH tests will most often be used to diagnose early or delayed puberty. 

Puberty is considered early if it starts before the age of 9 in female children and before the age of 10 in male children. It is considered to be delayed if it has not started by the age of 13 in female children or age 14 in male children.

To carry out the test, a specialist will need to take a blood sample from the patient. This will be done using a small needle, which may produce some small discomfort when inserted or withdrawn, but should produce no other side long term effects. This will normally take under 5 minutes.

The blood sample collected for an FSH test can produce several different results with some different meanings. These meanings will all depend on whether the patient is an adult male, an adult female, or a child, though all should be discussed with a doctor or healthcare provider to determine the best course of action for the future.