LH response to GnRH is a blood test to help determine if your pituitary gland can correctly respond to gonadotropin releasing hormone (GnRH). GnRH is a hormone produced in the hypothalamus.
Luteinizing hormone response to gonadotropin-releasing hormone
A blood sample is taken, and then you are given an shot of GnRH. After a specified time, other blood samples are taken so that LH can be measured.
For information on how the blood sample is taken, see: Venipuncture
No special preparation is necessary.
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
This test is used to tell the difference between primary and secondary hypogonadism , a condition in which the sex glands produce little or no hormones. In men, the sex glands (gonads) are the testes. In women, the sex glands are the ovaries.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
An excessive LH response suggests a problem within the ovaries or testes.
A reduced LH response suggests a problem with the hypothalamus or pituitary gland.
Abnormal results may also be due to:
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks related to having blood drawn are rare but may include:
In women, estrogen levels rise during the menstrual cycle until there is enough estrogen present to stimulate the release of GnRH and lutenizing hormone (LH).
Progesterone in high concentrations (for example, during the luteal phase of the menstrual cycle or during pregnancy) reduces the response of the pituitary gland to GnRH.
Webster RA. Reproductive function and pregnancy. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 25.
Ferri FF. Laboratory tests and interpretation of results. In: Ferri FF, ed. Ferri’s Clinical Advisor 2012. 1st ed. Philadelphia, Pa: Mosby Elsevier; 2011:section IV.