FSH (Follicle Stimulating Hormone)
Definition
FSH is a chemical messenger in the bloodstream that controls the function of specific cells and organs. Its roles differ by sex:
- In women: Controls the menstrual cycle and triggers egg development in the ovaries
- In men: Controls the amount of sperm produced by the testicles
- In children: Stays low until puberty, then rises to initiate sexual development
Purpose
Infertility evaluation (inability to conceive for 12+ months), menopause/perimenopause status, early or delayed puberty in children, pituitary or hypothalamic problems.
Results
- High FSH, indicates that the reproductive glands (ovary/testicle) are not producing enough hormone; the pituitary secretes more FSH to compensate. PCOS, premature ovarian insufficiency, Klinefelter syndrome or testicular damage
- Low FSH, pituitary or hypothalamic dysfunction; rapid weight loss or excessive exercise in women
Normal Values
Laboratory-specific. In women it varies with the phase of the menstrual cycle.
Risks and Limitations
Home urine FSH tests can only detect FSH that is higher than normal and should not be used to check whether you can become pregnant; they cannot accurately tell whether your ovaries are producing eggs.