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LH blood test
Alternative namesLH blood test measures the amount of luteinizing hormone (LH).
How the test is performed
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
How to prepare for the test
The health care provider may advise you to avoid drugs that may affect the test (see special considerations). For women in their reproductive years, the test may need to be done on a specific day of the menstrual cycle.
Infants and children:
How the test will feelWhen 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.
Why the test is performedThis test may be performed when a disorder associated with abnormal levels of LH is suspected.
LH is a protein hormone secreted by the anterior pituitary gland . In women, an LH surge at mid-cycle causes ovulation. For the next week or so, LH maintains the corpus luteum which synthesizes progesterone. If a woman does not become pregnant, the corpus luteum disintegrates after about 10 days. In men, LH stimulates production of testosterone by the Leydig cells of the testes .
What abnormal results meanGreater-than-normal levels of LH may indicate:
Lower-than-normal levels of LH may indicate hypopituitarism .
Additional conditions under which the test may be performed include:
What the risks are
Special considerationsRecent exposure to radioisotopes -- a recent nuclear medicine scan, for example -- can interfere with test results. Drugs that can decrease LH measurements include birth control pills, hormone replacement therapy, and testosterone.
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.
Update Date: 10/18/2003Francisco L. Gaudier, M. D., Maternal Fetal Medicine, Jacksonville, FL. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT