Gonadotropin-Releasing Hormone (GnRH)

What Is GnRH, How It Works, and Treatment with GnRH

Illustration of the anatomy of the pituitary and hypothalamus glands, which releases the hormone GnRH
GnRH is released in pulses by the hypothalamus. This then triggers to anterior pituitary gland to release the hormones FSH and LH. Stocktrek Images / Stocktrek Images / Getty Images

Quick Definition:

GnRH is an acronym for gonadotropin-releasing hormone. This hormone is released by the hypothalamus in the brain.

GnRH acts on receptors in the anterior pituitary gland. GnRH signals the pituitary gland to release the gonadotropin hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

FSH and LH then act on the ovaries in women and on the testes in men. They trigger the ovaries to mature and ovulate eggs, and, in men, trigger the testes to mature and produce sperm.

FSH and LH also stimulate the ovaries and testes to release their own hormones.

  • In the ovaries, estrogen, progesterone, and testosterone are produced.
  • In the testes, testosterone and estrogen are released.

GnRH is released in pulses and not continuously.

In men, these pulses come at a pretty consistent rate.

In women, the frequency of the pulses varies depending on where the body is in the menstrual cycle. For example, just before ovulation, the GnRH pulses are more frequent.

Other Names for GnRH

  • luteinizing hormone-releasing hormone (LHRH)
  • luteinising-hormone-releasing hormone
  • luliberin (intravenous medication that acts like GnRH in the body)
  • gonadorelin (intravenous medication that acts like GnRH in the body)

Testing with Gonadorelin

Gonadorelin is a medication that acts like the hormone GnRH in the body. It may be used in medical testing or as a treatment for delayed puberty or infertility.

Testing usually involves receiving injections of this hormone at a specific interval.

First, you’ll have a blood draw, before injection with the hormone.

Then, at a specific time, injection of gonadorelin just below the skin into the fatty tissue.

Next, after a set amount of time, you’ll have your blood drawn again.

This procedure – injection followed by blood draw – will be continued. The results will then be analyzed in a lab.

 

This test may be done in children with delayed puberty or adults with suspected hormonal imbalances.

Treatment with Gonadorelin via Lutrepulse pump

Women who are not ovulating may be treated with gonadorelin via a Lutrepulse pump. This is done if a lack of GnRH is the cause for anovulation.

Men who are not producing sperm may also be treated with a Lutrepulse pump.

The pump delivers a measured dose every 90 minutes over a period of weeks.

After treatment starts, in women, it usually takes two to three weeks for ovulation to occur. After ovulation, treatment usually continues for another two weeks through the luteal phase.

GnRH-a: GnRH Agonists and Antagonists

During IVF treatment, your fertility doctor needs to control the ovulatory cycle. Otherwise, the eggs can be ovulated too early. They would not be able to be retrieved and fertilized in the embryology lab if this occurred.

This is why you may need to take a GnRH agonist or GnRH antagonist.

Both of the medications produce a temporary menopausal state.

The difference between the drugs is that a GnRH agonist first produces a surge in the hormones FSH and LH and then they stop. A GnRH antagonist doesn’t produce that initial surge.

During IVF, you would then give yourself injections of the hormones FSH and LH to stimulate the ovaries to produce eggs.

GnRH agonists include:

  • Lupron
  • Synarel
  • Suprecur
  • Zoladex

GnRH antagonists include:

  • Antagon
  • Ganirelix
  • Orgalutran
  • Cetrotide

GnRH agonists may also be used to treat endometriosis and fibroids.

Sources:

Gonadorelin (Intravenous route, Injection route). Micromedex Detailed Drug Information for the Consumer [Internet]. PubMed Health. Accessed October 30, 2015. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0010500/?report=details

Gonadotropin-Releasing Hormone. You and Your Hormones. Society of Endocrinology. Accessed October 30, 2015. http://www.yourhormones.info/hormones/gonadotrophinreleasing_hormone.aspx

Medications for Inducing Ovulation: A Guide for Patients. American Society of Reproductive Medicine. Accessed February 3, 2008.

Continue Reading