A luteinizing hormone (LH) blood test measures the level of LH in the blood. LH is a hormone produced by the pituitary gland in both men and women. In women, LH plays a key role in the menstrual cycle and is responsible for triggering ovulation. In men, LH stimulates the production of testosterone in the testes.

The LH blood test is primarily used to evaluate reproductive health and diagnose conditions related to the ovaries or testes. It may also be used to monitor hormone replacement therapy in women who have had their ovaries removed or have gone through menopause.

During the test, a healthcare professional will draw a blood sample from your arm and send it to a laboratory for analysis. The results of the test are reported as the amount of LH present in your blood, usually measured in international units per liter (IU/L).

Normal levels of LH in the blood vary depending on the sex and age of the individual, as well as the specific laboratory and testing method used. In women, LH levels typically rise and fall during the menstrual cycle, with the highest levels occurring just before ovulation. In men, normal levels of LH are generally lower than in women.

Abnormal levels of LH may indicate a problem with the ovaries or testes, such as a tumor or other hormonal imbalance. In women, high levels of LH may indicate conditions such as polycystic ovary syndrome (PCOS), while low levels of LH may indicate a problem with the pituitary gland or hypothalamus. In men, low levels of LH may indicate a problem with testosterone production.

If your LH levels are abnormal, your healthcare provider may recommend additional tests, such as a follicle-stimulating hormone (FSH) blood test or imaging studies, to confirm the diagnosis and determine the appropriate treatment. Treatment may include medications to regulate hormone production, surgery to remove tumors or other growths, or other therapies depending on the specific condition.

Overall, the LH blood test is a useful tool for evaluating reproductive health and diagnosing conditions related to the ovaries or testes. If you have symptoms such as changes in menstrual cycle, infertility, or other hormonal imbalances, or have been diagnosed with a related condition, it is important to talk to your healthcare provider about whether an LH blood test or other tests may be appropriate for you.