Luteinizing hormone (Lutropin)
Men's/women's healthLuteinizing hormone (LH) is produced by the pituitary gland in the brain.
In women, it triggers ovulation and supports estrogen and progesterone production, while in men it stimulates the testes to produce testosterone.
Why this matters
Abnormal LH levels reveal much about reproductive health. In women, too little can cause irregular cycles or infertility, while very high levels often indicate menopause or ovarian insufficiency. In men, low LH leads to reduced testosterone, lowering energy, muscle mass, and libido. Lifestyle factors such as severe stress, undernutrition, and excessive exercise can suppress LH, while age and certain conditions raise it.
Measuring LH helps assess fertility, hormonal balance, and the function of ovaries or testes.
How this connects to other biomarkers
- In men, elevated LH with low Testosteron, total indicates the testicles themselves are failing (primary hypogonadism); low LH with low testosterone indicates a brain/pituitary cause (secondary hypogonadism).
- In women, an LH/FSH Ratio > 2 in the early follicular phase is a classic finding in PCOS (polycystic ovary syndrome).
- The LH surge mid-cycle triggers ovulation; persistently low LH across the cycle suggests hypothalamic amenorrhea (loss of periods due to stress, low body weight, or excessive exercise).
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