LH (luteinizing hormone) is a hormone produced by gonadotrophic cells in the anterior pituitary gland. In females, an acute rise of LH (LH surge) triggers ovulation, and development of the corpus luteum. In males, it has been called interstitial cell-stimulating hormone, as it stimulates Leydig cell production of testosterone. It acts synergicsically with FSH. It triggers ovulation when it "surges".

• It is high when negative feedback is missing from the gonad, causing unrestricted pituitary production of LH [and FSH]. High LH indicates:
  • Precocious puberty of pituitary or central origin, it may be in the reproductive range, rather than the low levels typical for their age
  • Premature menopause
  • Gonadal dysgenesis
  • Turner syndrome
  • Castration
  • PCOS
  • Certain forms of congenital adrenal hyperplasia
  • Testicular failure
  • Pregnancy (as bHCG can mimic LH)
• Low LH can result in:
  • Hypogonadism
  • Hypopituitarism
  • Eating disorder
  • Hyperprolactinemia
  • Hypogonadism