LH (Luteinizing Hormone)
Also written as: Luteinizing hormone, Lutropin
A pituitary hormone that triggers ovulation and drives testosterone production.
What it measures
The level of luteinizing hormone, a messenger from the pituitary gland at the base of the brain. In women it surges once per cycle to trigger ovulation; in men it steadily signals the testes to make testosterone.
Why a doctor orders it
Ordered alongside FSH for irregular periods, fertility evaluations, low testosterone work-ups, and puberty questions. The balance between LH, FSH, and the hormones they stimulate helps show whether a change starts in the brain's signaling or in the ovaries or testes.
What is generally associated with a higher result
Broadly associated with reduced ovarian or testicular response, with menopause, and with the normal surge that happens just before ovulation. A relatively high LH compared with FSH is also broadly associated with polycystic ovary syndrome.
What is generally associated with a lower result
Broadly associated with reduced pituitary or hypothalamic signaling, and with suppression by hormonal contraception, physical stress, low body weight, or heavy exercise training.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- The day of the menstrual cycle - a brief natural surge occurs mid-cycle
- Hormonal contraception, which suppresses it
- Intense exercise, low body weight, or recent major stress
- Biotin supplements, which can interfere with some lab methods
Questions to take to your appointment
- Could this have been drawn during the natural mid-cycle surge?
- How does this compare with my FSH, and what does that pattern suggest?
- Is there a specific point in my cycle when this test is most informative?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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