What is LH?
Luteinizing hormone (LH) is released by the pituitary gland. In women, a mid-cycle LH surge triggers ovulation; in men, LH stimulates the testes to produce testosterone. LH is measured alongside FSH to distinguish problems in the gonads from problems in the pituitary/hypothalamus.
Why it matters
LH helps pinpoint the cause of infertility, low testosterone, or menstrual irregularity whether the signal from the brain is the problem, or the gonads themselves.
What it measures
Serum LH concentration, interpreted with FSH, sex, and (in women) cycle phase.
Reference & optimal ranges
Reference ranges vary by lab, assay, age, and sex. The ranges below reflect commonly published adult intervals and are for education only always interpret results with the range printed on your own lab report and a clinician.
High LH suggests the gonads aren't responding (primary hypogonadism) or reflects menopause or PCOS.
Common symptoms
- Depends on cause: infertility, irregular cycles, low testosterone symptoms
Potential causes
- Primary gonadal failure
- Menopause
- PCOS (high LH:FSH ratio)
- Turner or Klinefelter syndrome
Low LH points to a pituitary or hypothalamic problem (secondary hypogonadism).
Common symptoms
- Low libido, infertility, absent periods
Potential causes
- Pituitary dysfunction
- Hypothalamic amenorrhea (stress, low body fat)
- High prolactin
- Anabolic steroid use
How to improve your LH
Lifestyle
Address energy availability
In hypothalamic amenorrhea, restoring adequate calories and body fat can normalize LH.
Nutrition
Adequate nutrition
Severe caloric restriction suppresses LH signaling.
Exercise
Balance training load
Excessive exercise without fueling suppresses the reproductive axis.
Sleep
Regular sleep
Supports normal pituitary rhythms.
Frequently asked questions
Scientific references
- LH (Luteinizing Hormone) Test Testing.com
- Luteinizing Hormone (LH) Levels Test MedlinePlus, U.S. National Library of Medicine
Educational information, not medical advice. This page is for general education and does not replace diagnosis or treatment by a licensed clinician. Do not start, stop, or change any medication, supplement, or treatment based on this content. Reference and optimal ranges vary between laboratories interpret your results with the range on your own report and a qualified professional.