Follicle-stimulating Hormone (FSH)
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- Also Known As:
- FSH
- Follitropin

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At a Glance
Why Get Tested?
To evaluate fertility issues, the health of your reproductive organs (ovaries or testicles), or pituitary function
In children, to evaluate early or delayed puberty
When To Get Tested?
For women, when you are having difficulty getting pregnant or are having irregular or no menstrual periods
For men, when your partner cannot get pregnant, or you have a low sperm count, low muscle mass or decreased sex drive
When your health care practitioner thinks that you have symptoms of a pituitary disorder or hypothalamic disorder
When a health care practitioner suspects that a child has delayed or earlier than expected puberty
Sample Required?
A blood sample is drawn by needle from a vein.
Test Preparation Needed?
No test preparation is needed, but a woman’s sample should be collected at specific times during her menstrual cycle.
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Health Records You Control
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What is being tested?
Follicle-stimulating hormone (FSH) is a hormone associated with reproduction and the development of eggs in women and sperm in men. This test measures FSH in the blood.
FSH is made by the pituitary gland, a small organ located in the center of the head behind the sinus cavity at the base of the brain. Control of FSH production is a complex system involving the hypothalamus in the brain, the pituitary gland, and the hormones produced by the ovaries or testicles. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary to release FSH and luteinizing hormone (LH), a closely related hormone also involved in reproduction.
- In women of childbearing age, FSH stimulates the growth and maturation of eggs (follicles) in the ovaries during the follicular phase of the menstrual cycle. The menstrual cycle is divided into the follicular and the luteal phases, with each phase lasting about 14 days. During this follicular phase, FSH initiates the production of estradiol by the follicle, and the two hormones work together in the further development of the egg follicle. Near the end of the follicular phase, there is a surge of FSH and luteinizing hormone. Release of the egg from the ovary (ovulation) occurs shortly after this surge of hormones. The hormone inhibin as well as estradiol and progesterone help control the amount of FSH released by the pituitary gland. FSH also facilitates the ability of the ovary to respond to LH.As a woman ages and menopause approaches, ovarian function wanes and eventually ceases. As this occurs, FSH and LH levels rise.
- In men, FSH stimulates the testicles to produce mature sperm and also promotes the production of androgen binding proteins. FSH levels are relatively constant in men after puberty. Less is known about FSH levels in aging men.
- 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. Concentrations begin to rise again before the beginning of puberty and the development of secondary sexual characteristics.
Disorders affecting the hypothalamus, pituitary, and/or the ovaries or testicles can cause the production of too much or too little FSH, resulting in a variety of conditions such as infertility, abnormal menstrual cycles, or early (precocious) or delayed puberty.
Common Questions
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The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
View Sources
Sources Used in Current Review
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Bayrak-Toydemir, P. et. al. (July 2017, Updated). Infertility. ARUP Consult. Available online at https://arupconsult.com/content/infertility. Accessed on 5/05/19.
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