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Follicle-stimulating hormone (FSH) is an important part of the reproductive system. It’s responsible for the growth of ovarian follicles. Follicles produce estrogen and progesterone in the ovaries and help maintain the menstrual cycles in women. In men, FSH is a part of the development of the gonads as well as sperm production.
The FSH test measures the level of FSH found in your blood. Your doctor will order an FSH test to find the underlying cause of symptoms affecting the reproductive system.
An FSH test is a simple blood test. Women might be asked to have this test done at a specific point in their menstrual cycle, usually the first couple of days.
In women, the most common reasons for an FSH test include:
In men, an FSH test may be done to:
An FSH test might be used to determine if a child is experiencing precocious puberty, which is early puberty. An FSH test may also be used to determine if a child is experiencing delayed puberty. This occurs when sexual features or organs don’t develop when they should.
Talk to your doctor about any prescription or nonprescription medications, dietary supplements, and vitamins you’re taking before any medical test is performed. You should tell your doctor about any types of birth control you use, such as the pill, an intrauterine device, or the patch, because this may play a role in your test results.
You should also discuss any existing medical disorders with your doctor, such as the following:
These conditions may be associated with FSH levels.
The test for the FSH level is simple and involves the following steps:
With any procedure, a small amount of risk is involved. Slight risks include:
FSH levels vary based on gender and age. They also vary depending on where a woman is in her monthly cycle. Each lab has a slightly different reference range. You should discuss your results with your doctor.
If you’re a woman with high FSH levels, this may indicate:
An increase in FSH may also indicate a reduction in the production of good quality eggs and embryos for fertilization. A common reason for this is your age. As you age, your fertility starts to decline and fewer eggs mature in your ovaries. The quality of the eggs that remain is lower than during earlier years.
The FSH test may be used with other tests that look at the levels of luteinizing hormone, estradiol, and progesterone to determine a woman’s ovarian reserve. The term "ovarian reserve" refers to a woman’s age-related fertility potential. A high FSH level means your chances of becoming pregnant may be lower than expected for your age. This doesn’t mean you have no chance of conceiving, but you may have more difficulty and need infertility treatment.
If you’re a man with high FSH values, this may indicate:
High FSH levels in children may mean that puberty is about to start.
Low FSH values may indicate that:
Stress and being severely underweight can affect FSH values.
Written by: Joanna Goldberg and Lydia Krause
Medically reviewed on: Jan 12, 2016: Nicole Galan, RN
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