Luteinizing Hormone (LH)
Also called: LH, Luteinizing hormone
LH triggers ovulation in women and drives testosterone production in men. Paired with FSH, it tells you whether reproductive trouble is at the gland (ovary / testis) or above it (pituitary / hypothalamus).
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What does Luteinizing Hormone (LH) measure?
LH is a pituitary hormone that pulses to the gonads — in women it triggers monthly ovulation and drives ovarian progesterone in the luteal phase; in men it stimulates Leydig cells to make testosterone. LH is interpreted together with FSH and the gonadal-output hormone (testosterone or estradiol) so the clinician can localise the problem. The pattern HIGH LH + low gonadal hormone = primary gonadal failure (ovary or testis isn't responding); LOW LH + low gonadal hormone = pituitary or hypothalamic failure. In women, timing within the menstrual cycle matters: LH surges mid-cycle (the basis of ovulation predictor kits), so a single value is interpretable only with cycle context.
What does a high Luteinizing Hormone (LH) level mean?
- Menopause / premature ovarian insufficiency — high LH + high FSH + low estradiol.
- Polycystic ovary syndrome (PCOS) — LH:FSH ratio often >2:1.
- Primary testicular failure — Klinefelter's, post-mumps, post-chemotherapy.
- Mid-cycle ovulatory surge — physiological, normal in fertile women.
- GnRH agonist therapy (paradoxical early phase) — therapeutic.
What does a low Luteinizing Hormone (LH) level mean?
- Hypogonadotropic hypogonadism — pituitary tumour, head trauma, congenital (Kallmann syndrome).
- Hyperprolactinaemia — high prolactin suppresses LH.
- Anorexia nervosa, athletic amenorrhoea — hypothalamic suppression from energy deficit.
- Chronic illness, severe stress — hypothalamic suppression.
- Oral contraceptives, anabolic steroids — exogenous feedback suppression.
When to discuss with a doctor
LH is rarely interpreted alone — always paired with FSH, testosterone (men) or estradiol (women), and prolactin. Specific contexts: woman with absent periods, suspected PCOS, infertility, premature menopause; man with low testosterone, infertility, suspected pituitary disease. Mediora.AI shows LH next to FSH and the gonadal hormone so the pattern (primary vs central) is visible; reproductive workup is endocrinology / gynaecology / andrology territory.
Related markers
Commonly confused with
- Follicle-Stimulating Hormone (FSH) Two pituitary hormones on the same form, differing by one letter. FSH drives the maturing of eggs or sperm; LH triggers ovulation and testosterone production. Their ratio matters more than either number alone.