LH plays a key role in regulating the reproductive system.

In women, LH triggers ovulation and stimulates the ovaries to produce estrogen and progesterone.

In men, LH stimulates the testes to produce testosterone.

Clinical uses include:

Assessing fertility problems in both men and women.

Diagnosing menstrual irregularities and polycystic ovary syndrome (PCOS).

Evaluating delayed or precocious puberty.

Supporting diagnosis of pituitary or gonadal dysfunction.

Often performed alongside FSH, estradiol, testosterone, and progesterone for a complete reproductive profile.

Analyte: Serum LH concentration (IU/L).

Normal Range (varies by sex, age, and menstrual cycle phase):

Women (follicular phase): ~2–12 IU/L

Women (mid‑cycle peak): ~18–56 IU/L

Women (luteal phase): ~1–14 IU/L

Men: ~1.5–9.3 IU/L

Abnormal Findings:

High LH: Primary ovarian failure, menopause, PCOS, testicular failure.

Low LH: Pituitary or hypothalamic dysfunction, stress, malnutrition.

Clinical Use:

Provides a marker of reproductive hormone regulation.

Helps guide fertility treatment and reproductive health management.

Supports diagnosis of endocrine and gonadal disorders.