LH response to GnRH is a blood test to help determine if your pituitary gland can correctly respond to gonadotropin releasing hormone (GnRH). LH stands for luteinizing hormone.
A blood sample is taken, and then you are given a shot of GnRH. After a specified time, more blood samples are taken so that LH can be measured.
No special preparation is necessary.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
GnRH is a hormone made by the hypothalamus gland. LH is made by the pituitary gland. GnRH causes (stimulates) the pituitary gland to release LH.
This test is used to tell the difference between primary and secondary hypogonadism. Hypogonadism is a condition in which the sex glands make little or no hormones. In men, the sex glands (gonads) are the testes. In women, the sex glands are the ovaries.
Depending on the type of hypogonadism:
This test may also be done to check:
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
An increased LH response suggests a problem in the ovaries or testes.
A reduced LH response suggests a problem with the hypothalamus gland or pituitary gland.
Abnormal results may also be due to:
Veins and arteries vary in size from one person 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 slight, but may include:
Reviewed By: Jennifer Sobol, DO, urologist with the Michigan Institute of Urology, West Bloomfield, MI. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.