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LH response to GnRH blood test
Luteinizing hormone response to gonadotropin-releasing hormone
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.
How the Test is Performed
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.
Blood sample is taken
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
LH
The LH blood test measures the amount of luteinizing hormone (LH) in blood. LH is a hormone released by the pituitary gland, located on the undersid...
How to Prepare for the Test
No special preparation is necessary.
How the Test will Feel
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.
Why the Test is Performed
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.
Hypogonadism
Hypogonadism occurs when the body's sex glands produce little or no hormones. In men, these glands (gonads) are the testes. In women, these glands ...
Depending on the type of hypogonadism:
- Primary hypogonadism starts in the testicle or ovary
- Secondary hypogonadism starts in the hypothalamus or pituitary gland
This test may be also be done to check:
-
Low
testosterone
level in men
Testosterone
A testosterone test measures the amount of the male hormone, testosterone, in the blood. Both men and women produce this hormone. The test described...
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Low
estradiol
level in women
Estradiol
An estradiol test measures the amount of a hormone called estradiol in the blood.
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Normal Results
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.
What Abnormal Results Mean
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:
-
Pituitary gland problems, such as release of too much hormone (
hyperprolactinemia
)
Hyperprolactinemia
Prolactin is a hormone released by the pituitary gland. The prolactin test measures the amount of prolactin in the blood.
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Large
pituitary tumors
Pituitary tumors
A pituitary tumor is an abnormal growth in the pituitary gland. The pituitary is a small gland at the base of the brain. It regulates the body's ba...
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Decrease in hormones made by the
endocrine glands
Endocrine glands
Endocrine glands release (secrete) hormones into the bloodstream. The endocrine glands include:AdrenalHypothalamusIslets of Langerhans in the pancrea...
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Too much iron in the body (
hemochromatosis
)
Hemochromatosis
Hemochromatosis is a condition in which there is too much iron in the body. It is also called iron overload.
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Eating disorders, such as
anorexia
Anorexia
Anorexia is an eating disorder that causes people lose more weight than is considered healthy for their age and height. People with this disorder may...
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- Delayed or absent puberty (Kallmann syndrome)
-
Lack of periods in women (
amenorrhea
)
Amenorrhea
Absence of a woman's monthly menstrual period is called amenorrhea. Primary amenorrhea is when a girl has not yet started her monthly periods, and sh...
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Risks
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 rare, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
References
Borawski D, Bluth MH. Reproductive function and pregnancy. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 25.
Gruber HA, Farag AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 24.
Haisenleder DJ, marshall JC. Gonadotropins. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric . 7th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 116.
Review Date: 9/26/2015
Reviewed By: Daniel N. Sacks MD, FACOG, obstetrics & gynecology in private practice, West Palm Beach, FL. Review Provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
