What does it measure?
Luteinizing hormone is made by the pituitary gland. In the menstrual cycle, a rise in LH helps trigger ovulation. In the testes, LH stimulates testosterone production. Blood testing is used with other hormones to investigate reproductive or pituitary questions. [1]
Before the test
- Sample
- A blood sample from a vein.
- Timing
- Record cycle day and hormone medicines. A blood LH result and a home urine ovulation test are different measurements.
What can the result mean?
A high value may be a normal midcycle surge or an expected finding after menopause. In other settings, high LH with low sex hormones can suggest reduced ovarian or testicular response. Low LH can reflect suppressed signaling, including effects of illness, medicines, or insufficient energy intake. [1]
When is it useful, and how is it read?
In a menstrual assessment, LH is read with cycle history, FSH, and estradiol. If the question is whether ovulation occurred, a clinician may use a properly timed progesterone result. In men with low testosterone, LH helps distinguish testicular from pituitary-related patterns. [1] [2] [3]
What can affect it?
LH is released in pulses, and a single blood sample captures only one moment. Cycle dates, hormone treatments, and the reason for testing matter. A serum LH result is also different from repeatedly using an ovulation-predictor urine test at home. [1]
An LH surge is a signal, not proof of egg release
The LH surge usually comes before ovulation. Detecting it, especially with a urine ovulation kit, helps estimate timing but provides indirect evidence: it cannot prove that an egg was released. [2]
Questions you might have
Can high LH be part of a normal cycle?
Yes. LH rises around ovulation. A result taken then has a different meaning from one collected at another cycle stage. [1]
Why is LH compared with FSH?
They are two pituitary signals acting on the ovaries or testes. Reading them with sex hormones helps explain where the signaling pattern may differ. [1]
What comes next?
Read LH with FSH and estradiol or testosterone, as appropriate. Your clinician can decide whether a repeat sample or another assessment would clarify the picture. Neither a lone LH value nor its ratio with FSH establishes a diagnosis of polycystic ovary syndrome. [1]
Could cycle timing or a hormone medicine explain this LH result?
The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.
Sources & references
Medical references & original research
- MedlinePlus — Luteinizing Hormone Lh Levels Test
- ASRM — Fertility evaluation of infertile women: a committee opinion (2021)
Books we consulted
References that informed our explanations of the test and its context.
- Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Elsevier; 2019.
Practical-section sources accessed: .
For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.
