Luteinizing hormone (LH) is a hormone produced in the pituitary gland in both males and females. In females, an “LH surge” (acute rise for 24-48 hours) triggers ovulation and the conversion of the residual follicle into a corpus luteum. In males, LH stimulates the production of testosterone.
Relatively high LH levels are frequently detected in the females with polycystic ovary syndrome, but usually still remain within the normal reproductive range. Persistently high LH levels in females may be a sign of premature menopause, or Turner syndrome. Persistently high LH levels in males can occur in Klinefelter syndrome, castration, or testicular failure. High LH levels in both genders may be indicative of gonadal dysgenesis or congenital adrenal hyperplasia. Elevated LH levels have been associated with a reduced fertilization rate in a variety of studies, as well as increased risk of miscarriage.
Diminished LH levels can lead to hypogonadism (gonadal function failure), which can cause low sperm production in males and amenorrhea (absence of menstruation) in females. Various conditions can contribute to abnormally low LH, including Pasqualini syndrome, Kallmann syndrome, hypothalamic suppression, hypopituitarism, eating disorders, and hyperprolactinemia.