Definition

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 underside of the brain.

Alternative Names

ICSH – blood test; Luteinizing hormone – blood test; Interstitial cell stimulating hormone – blood test

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

Your health care provider will ask you to temporarily stop medicines that may affect the test results. Be sure to tell your provider about all the medicines you take. These include:

• Birth control pills
• Hormone therapy
• Testosterone
• DHEA (a supplement)

If you are a woman of childbearing age, the test may need to be done on a specific day of your menstrual cycle. Tell your provider if you have recently been exposed to radioisotopes, such as during a nuclear medicine test.

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

In women, an increase in LH level at mid-cycle causes release of eggs (ovulation). Your doctor will order this test to see if:

• You are ovulating, when you are having trouble getting pregnant or have periods that are not regular
• You have reached menopause

If you are a man, the test may be ordered if you have signs of infertility or lowered sex drive. The test may be ordered if you have signs of a pituitary gland problem.