Gonadotropin-Releasing Hormone (GnRH): Purpose & Testing

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The pituitary gland in your endocrine system uses gonadotropin-releasing hormone (GnRH) to stimulate the production of follicle-stimulating hormone and luteinizing hormone. These gonadotropins (hormones) make the sex hormones testosterone, estrogen and progesterone. GnRH is vital to your sexual maturity, sex drive and fertility.

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Overview

What is gonadotropin-releasing hormone (GnRH)?

Everyone makes gonadotropin-releasing hormone (GnRH). When you’re an adolescent starting puberty, increasing levels of this hormone stimulate the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

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FSH and LH are gonadotropins (goh-NA-doh-TROH-pinz). Gonadotropins are essential to your reproductive health. They help your sex glands (gonads) mature and function. Gonads in females are ovaries and in males, they’re testicles.

What are other names for gonadotropin-releasing hormone (GnRH)?

Your healthcare provider may also use these terms to refer to gonadotropin-releasing hormone:

• GnRH
• Luliberin
• Luteinizing hormone-releasing hormone (LHRH)

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Function

What is the function of GnRH in females?

In the female reproductive system, GnRH indirectly stimulates your body’s production of estrogen and progesterone. These are the predominant female sex hormones that play a key role in ovulation and conception (your ability to get pregnant).

In the middle of your menstrual cycle:

1. Your body releases a higher level of estradiol. This is a type of estrogen that increases GnRH production
2. The increase in GnRH triggers a decrease in follicle-stimulating hormone and an increase in luteinizing hormone
3. These changes cause an ovary to release an egg (ovulation)

What is the function of GnRH in males?

In the male reproductive system, GnRH stimulates the production of:

• Luteinizing hormone, which affects how much testosterone and androgens (male sex hormones) your body makes
• Follicle-stimulating hormone, which affects sperm production

Anatomy

How does your body make GnRH?

Your endocrine system is responsible for producing GnRH. Nerve cells (neurons) in your brain’s hypothalamus gland make and release GnRH into your blood vessels. The hormone then travels to your pituitary gland at the base of your brain. GnRH stimulates your pituitary gland to make and release follicle-stimulating hormone and luteinizing hormone.

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What affects gonadotropin-releasing hormone levels?

GnRH levels are naturally low in children and rise during puberty. Afterward, testosterone, estrogen and progesterone control GnRH levels. Your body makes less GnRH when your sex hormone levels are high. It makes more GnRH when sex hormones are low. The one exception is during ovulation when a female’s body makes more GnRH and estradiol.

Conditions and Disorders

What happens if GnRH levels are too high?

An overproduction of GnRH is rare. Elevated levels may increase your risk of pituitary adenomas. These noncancerous (benign) tumors can cause your body to make too much follicle-stimulating hormone and luteinizing hormone. As a result, your body may make too much estrogen or testosterone. In children, high GnRH levels may cause precocious (early) puberty.

What happens if GnRH levels are too low?

Conditions associated with low GnRH levels in females include:

• Abnormal menstruation or amenorrhea (missed periods)
• Anovulation (no ovulation)
• Delayed sexual maturation and puberty
• Female infertility
• Low sex drive (hypogonadism)

Conditions associated with low GnRH levels in males include:

• Delayed sexual maturation and puberty
• Low sex drive (hypogonadism)
• Male infertility, low sperm count or azoospermia (no sperm in ejaculate)
• Testicular disorders like Kallman syndrome

How are gonadotropin-releasing hormone levels measured?

A blood test can measure levels of follicle-stimulating hormone and luteinizing hormone. This requires a simple blood draw. You don’t have to fast (not drink or eat) before getting this blood test. However, people who are menstruating may need to get a blood test during a certain time in their menstrual cycle (period).

A GnRH stimulation test can help determine high or low production of GnRH. During this test:

1. Your healthcare provider takes a blood sample
2. You receive an injection or IV of a lab-made GnRH or GnRH agonist
3. Your provider takes several blood samples spaced 15 to 30 minutes apart over two hours
4. You go home and return in 24 hours for a final blood draw
5. A lab checks the blood samples for levels of follicle-stimulating hormone, luteinizing hormone and sex hormones

What does an abnormal test result mean?

Results above the normal range suggest early puberty.

Care

How can I keep my endocrine system healthy?

These actions can keep your endocrine system healthy and functioning:

• Be physically active most days of the week
• Get adequate sleep
• Maintain a healthy weight by eating a balanced diet that’s low in fat and cholesterol
• Seek help to quit smoking and using tobacco products (nicotine can have a negative effect on your endocrine system and hormone levels)
• Take medications (if needed) to properly manage endocrine disorders like diabetes and thyroid disease

Additional Common Questions

What are gonadotropin-releasing hormone agonists?

GnRH medications can stop your pituitary gland from making the hormones that stimulate the production of sex hormones.

These medicines include:

• GnRH agonists (also called GnRH analogs), which activate your pituitary gland to make more luteinizing hormone and FSH. In time, your gland stops making both hormones. This stops the production of sex hormones.
• GnRH antagonists, which prevent your pituitary gland from responding to GnRH. As a result, the gland doesn’t make luteinizing hormone or sex hormones.

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What conditions do GnRH medicines treat?

Healthcare providers use GnRH medications to treat prostate cancer in males, as well as these conditions in females:

• Breast cancer
• Endometriosis
• Female infertility
• Heavy menstrual bleeding (menorrhagia)
• Premenstrual dysphoric disorder (PMDD)
• Uterine fibroids

A note from Cleveland Clinic

Your body’s production of gonadotropin-releasing hormone (GnRH) affects your sex hormone levels, libido and fertility. In children, too much GnRH can bring on early puberty, while too little hormone can delay puberty. You need GnRH to make follicle-stimulating hormone and luteinizing hormone. These hormones (gonadotropins) stimulate the production of testosterone, estrogen and progesterone. Healthcare providers also use GnRH medications to treat certain cancers and other conditions.

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Medically Reviewed.Last updated on 03/18/2022.

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References

Cleveland Clinic’s health articles are based on evidence-backed information and review by medical professionals to ensure accuracy, reliability and up-to-date clinical standards.

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Medically Reviewed.Last updated on 03/18/2022.

References

Cleveland Clinic’s health articles are based on evidence-backed information and review by medical professionals to ensure accuracy, reliability and up-to-date clinical standards.

• Endocrine Society. Brain Hormones (https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/gnrh). Accessed 3/18/2022.
• Kim HK, Kee SJ, Seo JY, et al. Gonadotropin-Releasing Hormone Stimulation Test for Precocious Puberty (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3190002/). Korean J Lab Med. 2011 Oct;31(4):244-249. Accessed 3/18/2022.
• LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. Gonadotropin Releasing Hormone (GnRH) Analogues (https://www.ncbi.nlm.nih.gov/books/NBK547863/). [Updated 2018 Mar 20]. Accessed 3/18/2022.
• Marques P, Skorupskaite K, Rozario KS, Anderson RA, George JT. Physiology of GNRH and Gonadotropin Secretion (https://www.ncbi.nlm.nih.gov/books/NBK279070/). [Updated 2022 Jan 5]. In: Feingold KR, Anawalt B, Boyce A, et al., eds. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Accessed 3/18/2022.
• National Cancer Institute (NCI). Gonadotropin-releasing hormone (https://www.cancer.gov/publications/dictionaries/cancer-terms/def/gonadotropin-releasing-hormone). Accessed 3/18/2022.
• You and Your Hormones (Society for Endocrinology). Gonadotropin-releasing hormone (https://www.yourhormones.info/hormones/gonadotrophin-releasing-hormone/). Accessed 3/18/2022.

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