Oestrogens . Patient guide
Luteinising Hormone (LH)
What is LH
Luteinising Hormone (LH) is a pituitary hormone that triggers ovulation in women and stimulates testosterone production in men. The LH-to-FSH ratio is one of the supporting clues in the PCOS diagnostic picture.
This biomarker entry is being clinically reviewed by our team. The factual content draws on UK guidance (NICE, NHS, Royal Colleges and the relevant speciality society where cited).
Reference range
Reported in IU/L. Final reports always carry the issuing laboratory's range, which is what your clinician will interpret against.
| Group | Range | Note |
|---|---|---|
| Cycling women, follicular (days 2-5) | 2.4 to 12.6 | IU/L |
| Cycling women, mid-cycle surge | 14 to 96 | briefly raised at ovulation |
| Cycling women, luteal phase | 1.0 to 11.4 | |
| Postmenopausal | 7.7 to 58.5 | |
| Adult men | 1.7 to 8.6 |
What it is
LH is produced by the anterior pituitary alongside FSH and surges mid-cycle to trigger ovulation in women. In the luteal phase it supports corpus luteum function and progesterone production. In men it stimulates Leydig cells to produce testosterone, and is interpreted alongside testosterone and FSH.
Why a clinician would order it
LH is requested in cycle irregularity work-up, ovulation confirmation (the LH surge marks ovulation), suspected PCOS (where an elevated LH-to-FSH ratio above 2 to 3 is a supporting clue), suspected hypopituitarism, and male infertility work-up alongside testosterone and FSH.
If your level is outside the range
Symptoms of low LH
- Amenorrhoea or oligomenorrhoea
- Anovulation (no LH surge)
- Reduced libido
- Men: small testes, low testosterone
What low can indicate. Hypothalamic amenorrhoea, hyperprolactinaemia (high prolactin suppresses LH), hypopituitarism, oral contraceptive use.
Symptoms of high LH
- Irregular periods or absent periods (PCOS pattern)
- Postmenopausal status (FSH and LH both raised)
- Men: primary testicular failure
What high can indicate. PCOS (LH typically higher than FSH, ratio above 2 is supportive), perimenopause and menopause, premature ovarian insufficiency, primary testicular failure in men. An LH surge captured at the right point of the cycle indicates imminent ovulation rather than disease.
Testing tips
Cycling women: days 2 to 5 timing for baseline LH. Hold oral contraceptives for at least 6 weeks if a true baseline is needed. The LH-to-FSH ratio is calculated by dividing LH by FSH; ratios consistently above 2 to 3 (with other features) support PCOS, ratios under 1 are typical of pure hypothalamic causes.
Where you can get this tested
Luteinising Hormone is included in the following WMG Health panels. Same-day appointments at our Harley Street clinic, with results clinician-reviewed.
Want a specific combination of markers we do not have a panel for? Build a custom panel and our clinicians will design one for you.
Sources
UK guidance our clinicians use when interpreting this marker.
This page is general patient information, not personal medical advice. A GMC-registered clinician will review your results and tailor any interpretation to you. See our Editorial Policy for how we write and review content.