Test Background LH stimulates the conversion of cholesterol to pregnenolone in the gonads and is the rate limiting step in the synthesis of progesterone and androgens. In women, the mid-cycle surge is essential for ovulation. LH is controlled by feedback of gonadal steroid concentrations at the pituitary, and higher levels are found in women after the menopause. In men, LH stimulates the Leydig cells in the testes to produce testosterone.
Clinical Indications Suspected infertility (men/women) Fertility treatment in assisted reproductive therapy Investigations of hypopituitarism and hypogonadism Differential diagnosis of primary ovarian insufficiency and menopause
Reference Range LH <20 years – see report
Male: 2-12 IU/L
Female follicular: 2-10
Female mid-cycle: 20-60
Female luteal: 4-14
Female post-menopause: >20