LH (luteinizing hormone)

Part of a feedback loop

The hypothalamus in your brain prompts the pituitary to release LH and its partner, follicle-stimulating hormone (FSH). Those hormones act on the ovaries or testes, which make estrogen, progesterone or testosterone. As sex hormone levels rise, they signal the brain to ease off, and when they fall, LH climbs.

Reading LH next to the sex hormone it controls is what makes it useful. The combination points to where in the chain a problem sits.

LH in men

In men LH stays fairly steady. The American Urological Association recommends measuring LH in anyone confirmed to have low testosterone.

• Low testosterone with high LH suggests the testes are not responding (primary hypogonadism).
• Low testosterone with low or normal LH suggests the signal from the brain is weak (secondary hypogonadism), which prompts tests such as prolactin.
• Testosterone therapy from outside the body usually suppresses LH, which is why it lowers sperm production.

LH in women and around menopause

Across a menstrual cycle, LH spikes just before ovulation; at-home ovulation kits detect that surge in urine. Persistently high LH throughout the month can suggest the ovaries are not working as expected, and high LH relative to FSH is sometimes seen in polycystic ovary syndrome.

As the ovaries wind down, LH and FSH rise. After 45, MedlinePlus notes that high levels usually reflect the normal menopause transition, so testing is often unnecessary to diagnose it. Testing is more useful for suspected early menopause before 45, or when symptoms are unclear.

Timing and interpretation

For women who still cycle, the day of the draw changes the meaning of the result, so note the first day of your last period. Hormonal contraceptives, hormone therapy, testosterone and some fertility drugs all alter LH. Always compare with the range on your lab report.

Where it comes up at HealifyMD

LH is often part of the work-up for low testosterone and for deciding between testosterone and treatments that stimulate your own production, such as enclomiphene. Your clinician interprets it alongside your symptoms and other hormones.

Preparing for an LH test

Bring a list of every hormone, supplement and fertility medicine you use, including creams and gels, because these can change the result. Men usually pair the draw with a morning testosterone test. Women who still have periods should track cycle days, since a single value taken without that context can be hard to read. If a result is unexpected, a repeat test is common before anyone changes treatment.