Educational information from Her Form — reviewed for accuracy by our health specialists.
Not a substitute for personal medical advice. Optional 1:1 consults with Robyn, our consulting women's-health specialist, are available on request.
What it is
LH surges mid-cycle to trigger the release of an egg. It is also chronically elevated in many women with PCOS.
Why it matters for women
An LH:FSH ratio above 2:1 on day 3 is a common PCOS marker. Mid-cycle LH confirms ovulation timing.
Optimal range
Day 3: 2–10 mIU/mL. LH:FSH near 1:1.
Standard lab range
Lab ranges are wide and rarely flag the ratio.
When it's high
- ↑PCOS
- ↑Perimenopause
- ↑Mid-cycle ovulation surge (normal)
When it's low
- ↓Hypothalamic amenorrhea
- ↓Pituitary dysfunction
References
- Endocrine Society — Female hormone health— Sex hormone assessment and interpretation in women
- Jean Hailes for Women's Health— Comprehensive women's hormone health guidance
- RANZCOG — Women's health guidelines— ANZ clinical standards for reproductive-age women
- NICE — Women's health guidelines— Evidence-based hormone and reproductive health guidance
References are provided for educational context only. Always interpret results with a qualified healthcare professional.
A note on interpretation. Ranges above are what our health specialists works to in healthy women. They are not a diagnosis — a single result always needs context from your symptoms, cycle phase and other markers.