Evidence-informed guide Glossary

Luteinising hormone (LH)

LH: a pituitary hormone that triggers ovulation, whose ratio to FSH is often raised in PCOS.

by Pasukan Editorial Panduan PCOS Last reviewed: 5 May 2026

Only a doctor can diagnose PCOS. This article is for education, not a substitute for medical advice.

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Why it matters for PCOS
FAQ
Sources

In simple terms: a pituitary hormone that triggers ovulation.

Why it matters for PCOS

LH (luteinising hormone) is released by the pituitary gland. A mid-cycle surge in LH triggers the release of an egg (ovulation), and LH also stimulates the ovaries to produce hormones. Some women with PCOS have a raised LH level or an elevated LH to FSH ratio, which can contribute to irregular ovulation.

That said, the LH/FSH ratio is not a stand-alone test for PCOS and is not raised in every patient. Hormone levels shift across the menstrual cycle, so results are interpreted in context with the timing of the test, your symptoms, and other hormones by a doctor.

This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.

FAQ

Frequently Asked Questions

What is luteinising hormone (LH)?

LH is a hormone released by the pituitary gland. A mid-cycle LH surge triggers ovulation, and LH also stimulates the ovaries to make hormones.

How does LH relate to PCOS?

Some women with PCOS have a raised LH level or an elevated LH to FSH ratio, but this ratio is not a stand-alone test for diagnosing PCOS.

Can the LH/FSH ratio confirm PCOS?

No. It is only one clue. A doctor considers symptoms, cycle pattern, other hormone levels, and sometimes ultrasound before making a diagnosis.

Sources

Teede HJ et al.. International evidence-based guideline for the assessment and management of polycystic ovary syndrome 2023. Fertility and Sterility / Endocrine Society. 2023.PubMed