FSH & LH Testing: Fertility, Menopause & Pituitary
Content last reviewed 2026-09-12 · Educational information — not medical advice
Quick answer
FSH and LH (gonadotropins) are the pituitary's signals driving the ovaries/testes. Tested for: menopause confirmation (high FSH), ovarian-reserve assessment (day-3), PCOS (LH:FSH ratio), and hypogonadism workups — with interpretation heavily dependent on cycle timing.
The pituitary-ovary dialogue
Pituitary FSH/LH stimulate follicle growth and sex-hormone production. Ovarian hormones feed back to suppress FSH/LH — when ovaries wane (menopause, POI), FSH/LH climb unchecked (the classic 'high FSH = low reserve'). The axis reads inversely: high FSH = ovary quitting, low FSH = pituitary failing or exogenous suppression.
Key interpretations
| Pattern | Meaning |
|---|---|
| High FSH + low estradiol + amenorrhea <40y | premature ovarian insufficiency |
| Day-3 FSH >10–12 | diminished ovarian reserve |
| LH:FSH >2:1 + elevated testosterone/AMH | PCOS signature |
| Low FSH + low LH + low testosterone/estrogen | hypogonadotropic (pituitary/hypothalamic) — a pituitary workup, not testicular/ovarian |
| Sustained high FSH + high LH in menopause | expected post-menopausal pattern |
Timing discipline
Ovarian-reserve FSH must be drawn DAY 2-4 of the menstrual cycle (estradiol rises later mask FSH). Menopause diagnosis relies on symptoms + amenorrhea + confirmation of elevated FSH; a single mid-cycle FSH misinterprets wildly. AMH now rivals day-3 FSH for reserve assessment without cycle-timing requirements.
Men: FSH/LH in hypogonadism
Elevated FSH/LH with low testosterone indicates PRIMARY (testicular) failure; low/normal FSH/LH with low testosterone indicates SECONDARY (pituitary) — a distinction steering MRI imaging versus direct replacement. Men with low T should always get FSH/LH to complete the picture.
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Frequently asked questions
Can I test FSH for menopause on any day?
Repeatedly elevated FSH (>25–40) in a reproductive-age woman with symptoms supports it — one draw is a strong hint, confirmation protocol best practice.
Does birth control affect FSH?
Powerfully — oral contraceptives suppress the entire axis rendering both FSH and LH uninterpretable for reserve/ovulation assessment.