FSH Test

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Also known as: Follicle-stimulating hormone
Formal name: Follicle-stimulating hormone

At a Glance

Why Get Tested?

To evaluate the function of your pituitary gland, which regulates the hormones that control your reproductive system

When to Get Tested?

If you are having difficulty getting pregnant or are having irregular menstrual periods, if your doctor thinks that you have symptoms of a pituitary, ovarian or testicular or hypothalamic disorder or when your doctor suspects that a child has delayed or earlier than expected sexual maturation.

Sample Required?

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) in females.

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 produced by the gonads (ovaries or testes), the pituitary gland, and the hypothalamus, such as gonadotrophin-releasing hormone (GnRH).

In women, FSH stimulates the growth and develpoment of ovarian follicles (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 make 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 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.

The Test

Common Questions

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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.