What is an FSH Test and Why Do You Need One?

Medically Reviewed By Amanda Kallen, MD
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An FSH test detects irregularities in your FSH levels. This can help doctors understand why you may be having issues with your sexual or reproductive functions.

Sex and gender exist on a spectrum. This article uses the terms “female” and/or “male” to refer to sex that was assigned at birth. 

Learn more about the difference between sex and gender here.

The pituitary gland, located in the brain, secretes follicle-stimulating hormone (FSH). FSH regulates sexual functions and reproductive development in humans. For instance, in males (sex assigned at birth), the FSH controls sperm production. While in females, FSH regulates the menstrual cycle and stimulates the growth of ova in the ovaries.

Changes in the FSH blood level above or below the standard level typically affect reproductive functions in males and females. Usually, an FSH blood test can detect these irregularities in FSH levels.

This article outlines the importance of the FSH test, indications, and various clinical interpretations of FSH blood levels.

Why do you need an FSH test?

Blood test tubes against a purple background
Angela Lumsden/Stocksy United

Your doctor uses an FSH test to assess your FSH levels. Your doctor may order an FSH test if you have concerns about your sexual or reproductive functions. The symptoms of irregular FSH levels vary for females and males.

For females, your doctor is likely to request a blood FSH test if you present with any of the following symptoms:

  • trouble conceiving after at least 1 year of trying
  • irregular menstrual cycle
  • prolonged absence of menstruation
  • menopausal or perimenopausal concerns

In males, your doctor may order an FSH blood test to:

  • identify the cause of infertility
  • assess the functions of your testicles
  • ascertain the cause of persistent low sex drive

In some cases, your doctor may request an FSH test if you have the following nonspecific symptoms:

The persistence of these nonspecific symptoms may indicate a pituitary gland disorder. Contact your doctor if you notice any of these symptoms for a protracted period.

Read about 10 surprising things you can detect with a blood test.

How do you prepare for an FSH test?

Generally, you do not have to prepare for an FSH blood test. However, some medications could interfere with the accuracy of the results. Your doctor may require you to stop certain medications, such as contraceptives or supplements, a few days before the test.

If you are in perimenopause, your doctor may prefer to conduct the test at a specific time in your menstrual cycle. Your doctor will typically recommend the most appropriate time for an FSH test after evaluating your menstrual cycle.

What happens during an FSH test?

For an FSH blood test, your healthcare professional uses a small needle to withdraw a blood sample into a tube or vial. You may feel a little sting or discomfort when the needle pierces your skin. However, the discomfort is only temporary. The test process usually takes a few minutes.

Additionally, there are urine test kits for at-home FSH level testing. These at-home test kits may indicate color changes when the FSH level in your urine is high. However, these urine test kits are not typically accurate and do not confirm you have any medical condition. Therefore, you should contact your doctor if you suspect you may have unusual FSH levels. 

Learn more about common blood tests here.

What do FSH levels mean?

FSH levels have clinical relevance and differ for males and females. Typically, your doctor interprets your FSH results alongside other clinical tests to make a diagnosis. Your FSH results alone are not enough to diagnose any conditions.

Below are some clinical interpretations of different FSH levels in males and females.

Normal FSH levels

Generally, a standard FSH level suggests that the testes, ovaries, and pituitary gland are functioning properly.

Regular FSH levels can also help distinguish different causes of infertility in males. For example, primary infertility related to irregular sperm production will produce different FSH levels than obstructive infertility causes. In an obstructive cause of infertility, FSH levels remain normal. 

High FSH levels in females

A high blood FSH level in females typically suggests either a dysfunction in the ovaries or a hyperfunctioning pituitary gland. When the pituitary gland functions regularly but the ovaries do not, FSH production increases in the blood, and the FSH blood level rises.

In contrast, if the pituitary gland is hyperfunctioning and the ovaries are normal, the gland secretes an excessive amount of FSH. This can occur with pituitary adenomas, for example. The FSH ramps up, which raises the FSH blood level.

The following are medical conditions associated with elevated FSH levels in females: 

High FSH levels in males 

High levels of FSH in males typically indicate a hyperactive pituitary gland or irregularities in the testes. Dysfunctional testes may not respond to FSH. Thus, the FSH blood level can rise even when the pituitary gland functions properly.

Conversely, when the pituitary gland hyperfunctions because of pituitary adenomas, the FSH production in the blood increases.

Some clinical conditions with high FSH in males include Klinefelter syndrome and testicular damage due to chemotherapy or radiotherapy.

Low FSH levels in females

Low levels of FSH typically indicate a dysfunction in the hypothalamus or anterior pituitary gland. The hypothalamus is the part of the brain that controls the body’s pituitary gland functions and other hormonal activities. A low blood level of FSH may mean any of the following:

  • inadequate growth of ovarian follicles, which contain eggs
  • pituitary gland dysfunction
  • dysfunctional hypothalamus
  • severe underweight

Low FSH levels in males

In males, low FSH levels typically suggest a condition of the pituitary gland or hypothalamus. This may affect spermatogenesis, a cell differentiating process that ensures the production of sperm. It may also affect the quality of sperm produced in the testes.

Summary

The FSH test is essential to provide your doctor with information regarding your FSH levels. FSH controls male and female reproductive functions. Therefore, an irregular FSH blood level typically affects reproductive and sexual activities in males and females.

The symptoms of irregular FSH blood levels differ in males and females. Generally, females with atypical FSH may experience an irregular menstrual cycle, prolonged menstruation, and infertility. Males may experience low libido and infertility.

Your doctor will typically recommend discontinuing some medications a few days before the test.

Generally, a high FSH level indicates an anomaly in the sperm or egg counts. In contrast, a low FSH level typically suggests an anterior pituitary gland or hypothalamus disorder.

If you suspect you may have symptoms of irregular FSH levels, consult your doctor.

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Medical Reviewer: Amanda Kallen, MD
Last Review Date: 2022 Aug 3
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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  3. Orlowski, M., et al. (2022). Physiology, follicle stimulating hormone. https://www.ncbi.nlm.nih.gov/books/NBK535442/