Luteinizing hormone (LH) is a hormone produced by the pituitary gland in the brain. It plays a crucial role in regulating the reproductive system in both males and females. In women, LH triggers ovulation and helps maintain the menstrual cycle, while in men, it stimulates the production of testosterone. LH levels fluctuate throughout the menstrual cycle, peaking just before ovulation. This hormone is essential for fertility and is often measured in medical tests to assess reproductive health. Abnormal LH levels can indicate various health issues, including polycystic ovary syndrome (PCOS) or hypogonadism.