Follicle-Stimulating Hormone (FSH)

Take-home points

• If you suspect infertility or experience symptoms of low testosterone, a healthcare professional can offer you an FSH test for investigation.
• Normal FSH levels for adult males are typically between 1.5 and 12.4 IU/L.
• Abnormal FSH levels could indicate hypogonadism and a lack of sperm production.

‍What is FSH and what does it do?

FSH is an abbreviation of the follicle-stimulating hormone, which plays a critical role in reproductive health. The pituitary gland produces FSH in response to signals from the hypothalamus in the brain.

In women, the main functions of FSH are to stimulate estrogen production and the maturation of ovarian follicles, which contain the eggs released during ovulation. In men, FSH is used to facilitate the production of sperm in the testes.¹

Why might I need an FSH test?

A healthcare professional might recommend an FSH test to evaluate various conditions related to reproductive health. If a doctor suspects any fertility problem, pituitary gland disorder, or delayed or precocious puberty, measuring FSH is generally advised to investigate a potential dysfunction of the hypothalamus–pituitary–gonads system (“HPG axis”).¹

In men, an FSH test is mostly used to assess patients who are infertile or experiencing symptoms of hypogonadism, which is a condition where the body does not produce enough testosterone. ¹

What are normal FSH levels?

Normal FSH levels for adult males are typically between 1.5 and 12.4 IU/L.

What do high or low FSH levels indicate?

A healthcare professional should communicate what your FSH results mean to you. The same FSH result can be interpreted differently from one patient to another, depending on differences in health status, reported symptoms, and other relevant test results.

If you have an abnormal FSH reading, you should be advised to book another test to confirm the abnormality. Your FSH levels naturally vary—though this is more apparent in women due to the menstrual cycle.

Generally speaking, high levels of FSH could indicate a lack of sperm production and an increased risk of infertility. The possible reasons for a high FSH reading include health conditions like Klinefelter syndrome, pituitary gland disorders, and testicular failure or damage. In combination with low total testosterone, a high FSH level indicates testicular failure and is used to diagnose primary hypogonadism.²

On the other hand, whereas the pituitary gland works in overdrive in primary hypogonadism, secondary hypogonadism centres on defects in the brain or pituitary that result in insufficient LH and FSH production. Secondary hypogonadism is therefore associated with low or low-normal LH and FSH levels.

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References

1. Dandona P, et al. Int J Clin Prac 2010;64(6):682–696.

2. Rose M, et al. Endocrine Reviews 2000;21(1):5–22.