LH (Luteinizing Hormone) Test
An LH test measures luteinizing hormone, a signal released by the pituitary gland that tells the ovaries or testes what to do. It is one of the most common markers ordered when someone is looking at fertility, cycle changes, or hormone production.
About this test
Luteinizing hormone is made in the pituitary gland at the base of the brain and travels through the bloodstream to the gonads. In women, a sharp rise in LH is the trigger for ovulation, which is why home ovulation predictor kits are built around it.
That relationship is what makes the test useful. When a sex hormone measurement looks unexpected, LH helps a clinician see whether the signal from the brain is part of the story or whether the gonads themselves are responding differently. It separates an upstream question from a downstream one.
Test details
| Quest code | 615 |
|---|---|
| Methodology | Immunoassay |
| Sample type | 1 mL serum |
| Collection | Quest patient service center |
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Additional details
What luteinizing hormone does
LH is part of a feedback loop between the brain and the gonads. The hypothalamus prompts the pituitary, the pituitary releases LH and follicle-stimulating hormone, and the ovaries or testes respond by producing estrogen, progesterone, or testosterone. Those sex hormones then feed back to the brain, which adjusts the signal up or down. The loop runs continuously, adjusting throughout the day and, in women, across the menstrual cycle.
Because of that loop, LH and the hormone it controls are usually most informative when read together. A clinician looks at the pair to understand which part of the system is behaving unexpectedly.
Why timing affects the result
LH is released in bursts rather than at a steady rate, so two samples taken hours apart can differ. In menstruating women the variation is much larger: LH climbs steeply just before ovulation and falls again afterward, so the same person can produce very different measurements depending on the cycle day.
This is why a clinician may ask for collection on a specific day, or for testing repeated across a cycle. If your periods are irregular or you are not menstruating, say so when discussing results, because it changes how the timing is understood.
Tests commonly paired with LH
LH is almost always considered next to follicle-stimulating hormone, since the two are released together and their relationship carries more meaning than either alone. Depending on the question, a clinician may also review estradiol, progesterone, testosterone, prolactin, thyroid markers, or anti-Müllerian hormone.
Read as a group, these markers describe both the signal and the response. That combined view is what a clinician uses to decide whether anything needs further attention, and it is far more informative than a single hormone measurement.
Ordering, pricing, and collection
This is one of the more affordable single hormone tests available on the site, and the cash price shown by the order button is the full amount you pay. There is no insurance claim, no membership, and no separate charge for a physician's order, since that is arranged for you. The draw takes a few minutes at a participating Quest patient service center, .
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does an LH test measure?
It measures luteinizing hormone, a pituitary signal that prompts the ovaries to ovulate and the testes to produce testosterone. It describes the instruction being sent rather than the hormone being produced.
How much does an LH blood test cost?
The cash price is listed next to the order button on this page and includes the physician's order. No insurance is billed and there is no separate consultation fee.
Is a blood LH test the same as an ovulation predictor kit?
Both look at the same hormone, but home kits check urine for the surge that precedes ovulation, while a blood test reports the amount circulating at the moment of collection. Clinicians use the blood measurement in a broader hormone evaluation.
When in my cycle should the sample be collected?
It depends on the question. Because LH changes sharply around ovulation, a clinician often specifies a cycle day so results can be interpreted and compared properly.
Why is LH usually ordered with FSH?
The two hormones are released together and their relationship carries more information than either does alone. Clinicians typically review them as a pair alongside the relevant sex hormones.