Luteinizing Hormone (LH)

Luteinizing hormone (LH) is a pituitary hormone that drives ovulation in women and testosterone production in men. Your LH level is usually read next to FSH and sex hormones to show whether a reproductive issue starts in the gonads or higher up in the brain.

Ranges vary by cycle phase, menopause, lab, and assay, so compare to the range on your own lab report.

What LH measures

LH is released by your pituitary gland in response to signals from the hypothalamus. In women, a mid-cycle LH surge triggers the ovary to release an egg, while in men LH prompts the Leydig cells in the testes to produce testosterone. Measuring LH helps show how well this signaling loop between your brain and your gonads is working.

What high or low levels mean

High LH often means your gonads are underperforming and the pituitary is compensating by pushing harder. In women this pattern fits menopause or primary ovarian failure, and in men it points toward primary testicular failure. Polycystic ovary syndrome frequently shows raised LH with a high LH to FSH ratio. Low LH suggests the signal is being dampened higher up, in the pituitary or hypothalamus, from causes such as a pituitary disorder, chronic stress, low energy availability, or heavy training. Because a single value can mislead, you should note where you are in your cycle when tested and repeat borderline results. Always read LH together with FSH, since the two gonadotropins move together and their ratio carries most of the diagnostic weight.

LH FAQ

What does a high LH level mean?

A high LH level usually means your ovaries or testes are not responding well, so the pituitary raises its output to compensate. It is common after menopause, in primary gonadal failure, and in some cases of polycystic ovary syndrome.

When should LH be tested during the menstrual cycle?

For a baseline reading, clinicians often draw LH on day 3 of your cycle. To confirm ovulation timing, testing targets the mid-cycle surge, so the day of the test changes the numbers you should expect.

Can LH levels affect fertility?

Yes. LH triggers ovulation and supports testosterone production, so levels that run too high or too low can disrupt egg release or sperm production. Your clinician reviews LH with FSH and sex hormones before drawing conclusions.

Read alongside follicle-stimulating hormone, estradiol, and total testosterone for the fuller reproductive picture.

Sources

• University of Michigan Medical Laboratories, Luteinizing Hormone.

• Medical News Today, Luteinizing hormone (LH) test.