LH
What it measures, and what changes the number.
LH, or luteinizing hormone, is made by the pituitary gland and signals the ovaries or testes. In women it triggers ovulation and supports progesterone production; in men it stimulates the testes to make testosterone. The test measures the LH concentration in the blood.
It is nearly always ordered with FSH, the partner pituitary hormone, and read against the hormones it controls, such as estradiol and progesterone in women and total testosterone in men. Prolactin is often included as well.
LH is released in pulses and changes greatly across the menstrual cycle, with a surge around ovulation, so the cycle day of the sample matters and is often specified by the ordering clinician. Morning sampling is common. Hormonal contraception affects the result, and immunoassays vary between manufacturers. Labs may print it as Hormona Luteoestimulante (LH).
Reference ranges labs publish
Each lab states an interval for its own method and the population it measured. They differ, they are not interchangeable, and none of them is a verdict on a single result.
- Men, 18 years and over: 1.3 to 9.6 IU/L · ECLIA (immunoassay) · Source: Mayo Clinic Laboratories, LH (Luteinizing Hormone (LH), Serum) (read 2026-09-24)
- Men, adults: 1.7 to 8.6 mIU/mL · ECLIA (immunoassay) · Source: Labcorp, 004283 (Luteinizing Hormone (LH)) (read 2026-09-24)
- Women, follicular phase: 1.9 to 14.6 IU/L · ECLIA (immunoassay) · Source: Mayo Clinic Laboratories, LH (Luteinizing Hormone (LH), Serum) (read 2026-09-24)
- Women, midcycle (ovulation): 12.2 to 118 IU/L · ECLIA (immunoassay) · Source: Mayo Clinic Laboratories, LH (Luteinizing Hormone (LH), Serum) (read 2026-09-24)
- Women, luteal phase: 0.7 to 12.9 IU/L · ECLIA (immunoassay) · Source: Mayo Clinic Laboratories, LH (Luteinizing Hormone (LH), Serum) (read 2026-09-24)
- Women, postmenopausal: 5.3 to 65.4 IU/L · ECLIA (immunoassay) · Source: Mayo Clinic Laboratories, LH (Luteinizing Hormone (LH), Serum) (read 2026-09-24)
- Women, follicular phase: 2.4 to 12.6 mIU/mL · ECLIA (immunoassay) · Source: Labcorp, 004283 (Luteinizing Hormone (LH)) (read 2026-09-24)
- Women, midcycle (ovulation): 14 to 95.6 mIU/mL · ECLIA (immunoassay) · Source: Labcorp, 004283 (Luteinizing Hormone (LH)) (read 2026-09-24)
- Women, luteal phase: 1 to 11.4 mIU/mL · ECLIA (immunoassay) · Source: Labcorp, 004283 (Luteinizing Hormone (LH)) (read 2026-09-24)
- Women, postmenopausal: 7.7 to 58.5 mIU/mL · ECLIA (immunoassay) · Source: Labcorp, 004283 (Luteinizing Hormone (LH)) (read 2026-09-24)
Often read alongside: FSH, Estradiol (E2), Progesterone, Total testosterone, Prolactin