Luteinizing Hormone (LH)
Evaluates reproductive and pituitary function.
Content last reviewed 2026-09-12 · Educational information — not medical advice
It is commonly considered when evaluating Polycystic Ovary Syndrome, Endometriosis, Erectile Dysfunction; people with Alopecia, Erectile dysfunction, Infertility may have it ordered as part of their work-up.
What is the Luteinizing Hormone (LH)?
The Luteinizing Hormone (LH) is a laboratory blood test that measures luteinizing hormone (LH), the pituitary trigger for ovulation and sex-hormone production.
How the Luteinizing Hormone (LH) works
Quantitative blood measurement of the relevant hormone (hCG, AMH, FSH, LH, progesterone), interpreted against gestational age or menstrual-cycle timing where applicable.
Why healthcare providers order it
Confirming and dating pregnancy, evaluating fertility and ovarian reserve, investigating irregular cycles or suspected ectopic pregnancy, and monitoring assisted-reproduction cycles.
Interpreting your results
Understanding fertility & pregnancy results
- hCG: rises predictably in early viable pregnancy (~doubling every 48–72 hours); slow rise or plateauing needs urgent clinical evaluation to exclude ectopic pregnancy.
- AMH: a rough ovarian-reserve indicator — informative for IVF planning, not a fertility guarantee in either direction.
- Progesterone: mid-luteal elevation confirms ovulation occurred.
What your LH result means
Interpreted against cycle timing in fertility workups; an LH surge precedes ovulation.
Reference intervals vary by laboratory, instrument, age, sex, and — for hormones — collection time. Always compare your value against the range printed on your own report, and review results with a qualified healthcare professional who knows your history. This guide is educational and does not diagnose.
Understanding your lab report
- Find the reference interval printed beside your value on the report — that pairing defines 'normal' for this lab run.
- Note the units. mmol/L vs mg/dL, ng/mL vs µg/L — numbers mean nothing across unit systems.
- Look at flags (H/L) but read the degree: barely-outside values behave differently than multiples of the limit.
- Trends outrank snapshots. A series of results tells your provider far more than any single draw.
Conditions that may involve Luteinizing Hormone (LH)
Symptoms that may lead to this test
Frequently asked questions
What does the Luteinizing Hormone (LH) measure?
It measures luteinizing hormone (LH), the pituitary trigger for ovulation and sex-hormone production.
Do I need to fast before the Luteinizing Hormone (LH)?
Fasting is not routinely required for this test; follow any instructions from your provider or laboratory.
How soon do Luteinizing Hormone (LH) results come back?
Most routine assays return within 1–3 business days; specialty methods can extend that to a week or more.
Can an abnormal Luteinizing Hormone (LH) result mean something serious?
Abnormal results range from benign to urgent; degree, direction, and trend — reviewed by a clinician who knows your history — determine what happens next.
Sources & data provenance
- Family-specific guidance compiled from standard clinical laboratory medicine references