What does the Luteinising Hormone test measure?

Why is Luteinising Hormone measured?

LH is interpreted alongside FSH as a ratio in the evaluation of polycystic ovary syndrome (PCOS), where an elevated LH:FSH ratio (typically >2:1) — alongside hyperandrogenism and oligo-ovulation — supports the diagnosis. Elevated LH with elevated FSH in the postmenopausal pattern confirms gonadotropin release following loss of ovarian negative feedback. The LH:FSH ratio is a core interpretive metric in female hormone evaluation rather than either marker in isolation.

Reference ranges

Standard reference

Highly cycle-phase, sex- and age-specific. Premenopausal follicular ~2.4–12.6 mIU/mL, mid-cycle surge much higher; postmenopausal ~7.7–58.5 mIU/mL; adult men ~1.7–8.6 mIU/mL # REVIEWER FLAG: Phase/sex/age-banded and assay-specific — confirm Quest ranges.

Functional medicine optimal

Early follicular LH:FSH ratio: 1:1 (ratio approaching 2:1 or greater in the follicular phase is associated with PCOS). # REVIEWER FLAG: LH:FSH ratio cut-offs for PCOS assessment vary between diagnostic frameworks — reviewer to confirm preferred ratio threshold.

Units

mIU/mL, IU/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.