Luteinizing hormone (LH) is produced by the pituitary gland, a small gland located at the base of the brain. In females, LH plays a vital role in the menstrual cycle and in the production of estrogen and progesterone, two hormones that regulate the menstrual cycle and fertility. In males, LH helps regulate the production of testosterone, a hormone that plays a role in the development of male secondary sexual characteristics and fertility.
An LH test is a blood test that measures the luteinizing hormone levels in the blood. The test helps diagnose and treat conditions that affect the menstrual cycle, fertility, and hormone production in both males and females. Medical experts also use it to help diagnose conditions that affect the pituitary gland or the hypothalamus, a part of the brain that helps regulate the production of hormones.