At a Glance
Why Get Tested?
When to Get Tested?
If you are having difficulty getting pregnant or are having irregular menstrual periods (in order to identify or rule out ovarian failure/menopause in women and sperm production failure in men); if your doctor thinks that you have symptoms of a pituitary, ovarian, testicular or hypothalamic disorder; when your doctor suspects that a child has delayed or earlier than expected sexual maturation (or delayed or early growth).
A blood sample taken from a vein in your arm
Test Preparation Needed?
No special preparation is required for the test, but the blood sample should be taken at the start of a women's cycle (days 1 to 4 if the cycles are regular)
The Test Sample
What is being tested?
Follicle-stimulating hormone (FSH) is made by the pituitary gland in the brain. Control of FSH production is a complex system involving hormones, such as gonadotrophin-releasing hormone (GnRH) produced by the gonads (ovaries or testes), the pituitary gland, and the hypothalamus.
In women, FSH stimulates the growth and development of ovarian follicles (unfertilised eggs) during the follicular phase of the menstrual cycle. This cycle is divided into two phases, the follicular and the luteal, by a mid-cycle surge of FSH and luteinising hormone (LH). Ovulation (release of the egg from the ovary) occurs shortly after this mid-cycle surge of hormones. During the follicular phase, FSH initiates the production of oestradiol by the follicle, and the two hormones work together in the further development of the egg follicle. During the luteal phase, FSH stimulates the production of progesterone. Both oestradiol and progesterone help the pituitary control the amount of FSH produced. At the time of menopause, the ovaries stop functioning and FSH levels rise. During pregnancy, oestrogen levels are high and this makes FSH undetectable.
In men, FSH stimulates the testes to produce mature sperm. FSH levels are relatively constant in men after puberty.
In infants and children, FSH levels rise shortly after birth and then fall to very low levels (by 6 months in boys and 1-2 years in girls). At about 6-8 years, levels again rise with the beginning of puberty and the development of secondary sexual characteristics.
How is the sample collected for testing?
A blood sample is taken by needle from a vein, normally in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No, but in a women, the sample should be taken in the first 4 days of her cycle if the periods are regular (day 1 is the first day of full bleeding). If the test is for menopause, for example, and periods are stopping then the FSH can be taken at any time but occasionally repeat samples may be needed. This is because it can take a couple of years for the ovaries to stop working completely and results may be contradictory when the menopause first starts to occur in the first 4 days of her cycle.
Ask a Laboratory Scientist
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.