Luteinizing Hormone

A luteinizing hormone test measures the amount of luteinizing hormone (LH) in a sample of blood or urine. LH is produced by the pituitary gland.

• In women, LH helps regulate the menstrual cycle and egg production (ovulation). The level of LH in a woman's body varies with the phase of the menstrual cycle. It increases rapidly just before ovulation occurs, about midway through the cycle (day 14 of a 28-day cycle). This is called an LH surge. Luteinizing hormone and follicle-stimulating hormone levels rise and fall together during the monthly menstrual cycle.
• In men, LH stimulates the production of testosterone, which plays a role in sperm production.