LH blood test

LH blood test measures the amount of luteinizing hormone (LH).

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 an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band 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 band 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.

For an infant or young child:

The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any continued bleeding.

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.

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 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.

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