⚠️ Educational only. LabPlain does not provide medical advice or diagnosis. Always discuss your specific results with your healthcare provider.
What this test measures
LH stands for luteinizing hormone — a hormone produced by the pituitary gland, a small gland located at the base of the brain. LH plays a major role in regulating reproductive hormones and fertility in both women and men.
In women, LH helps control the menstrual cycle and triggers ovulation — the release of an egg from the ovary. LH levels normally rise sharply right before ovulation. In men, LH stimulates the testes to produce testosterone.
Doctors order an LH test when evaluating fertility issues, irregular periods, menopause, low testosterone, delayed puberty, pituitary disorders, or conditions like PCOS (polycystic ovary syndrome).
Normal reference range
Women (varies by cycle phase): 1.9–12.5 IU/L | Men: 1.7–8.6 IU/L
LH levels fluctuate significantly throughout the menstrual cycle. A result that's considered normal during ovulation may be abnormal during another phase of the cycle.
After menopause, LH levels naturally rise because the ovaries produce much less estrogen and progesterone.
🩸 Why cycle timing matters
For women who still menstruate, the day of the menstrual cycle matters when interpreting LH. Doctors often order LH testing on day 2–5 of the cycle for fertility evaluation, or around ovulation when checking for an LH surge.
What your result might indicate
↑ If High
High LH may occur during ovulation, menopause, PCOS, primary ovarian failure, or testicular failure. Elevated LH can also point to problems where the ovaries or testes aren't responding properly to hormonal signals.
↓ If Low
Low LH may suggest pituitary or hypothalamic disorders, eating disorders, excessive exercise, chronic illness, or hormonal suppression. Low LH can contribute to infertility or low testosterone.
Symptoms associated with abnormal LH
↑ High LH Symptoms
Irregular or absent periods
Infertility
Hot flashes or menopause symptoms
Acne or excess facial hair (PCOS)
Low testosterone in men
Reduced sex drive
Erectile dysfunction
Difficulty conceiving
↓ Low LH Symptoms
Missed or absent periods
Infertility
Low sex drive
Fatigue
Low testosterone symptoms
Delayed puberty
Reduced muscle mass
Difficulty ovulating
Common causes of abnormal LH
What can raise LH?
High LH commonly occurs during ovulation and after menopause — both are completely normal situations. Outside those situations, elevated LH may be linked to PCOS, ovarian failure, Turner syndrome, or testicular failure in men.
In men, high LH with low testosterone may indicate the testes are not responding properly, causing the pituitary gland to release extra LH in an attempt to stimulate testosterone production.
What can lower LH?
Low LH is often caused by problems involving the pituitary gland or hypothalamus — the parts of the brain that regulate hormone production. Other causes include chronic stress, eating disorders, excessive endurance exercise, severe illness, obesity, and certain medications such as opioids or anabolic steroids.
Very low body fat or severe calorie restriction can also suppress LH production, especially in athletes or people with restrictive eating patterns.
Tests often ordered alongside LH
LH is almost always interpreted together with other hormone tests. Your doctor may also order:
FSH (Follicle-Stimulating Hormone) — often paired with LH for fertility and menopause evaluation
Estradiol — helps assess ovarian function and menstrual health
Testosterone — evaluated in men with low libido, infertility, or fatigue
Prolactin — elevated prolactin can suppress LH production
TSH (Thyroid-Stimulating Hormone) — thyroid disorders can affect reproductive hormones
What to do next
An abnormal LH result doesn't automatically mean something is seriously wrong. LH changes naturally based on age, sex, menstrual cycle timing, menopause status, stress, medications, and overall health. Your doctor will interpret the result together with your symptoms, medical history, and related hormone tests.
Questions to ask your doctor
01Was this test done at the correct point in my menstrual cycle?
02Do I also need FSH, estradiol, or testosterone testing?
03Could my medications or stress levels affect this result?
04Does this result suggest menopause, PCOS, or a pituitary issue?
05Should I see a fertility specialist or endocrinologist?
06Would repeat testing help confirm the pattern?
Frequently asked questions
What does LH do in women?
LH triggers ovulation and helps regulate the menstrual cycle. Right before ovulation, LH levels surge sharply to signal the ovary to release an egg.
What does LH do in men?
In men, LH signals the testes to produce testosterone. Low or high LH can both affect testosterone levels, fertility, sex drive, and energy.
Can PCOS cause high LH?
Yes. Many women with PCOS have elevated LH levels or an increased LH-to-FSH ratio. However, LH alone cannot diagnose PCOS — doctors also consider symptoms, ultrasound findings, and other hormone tests.
Does menopause raise LH?
Yes. After menopause, estrogen levels fall significantly, causing the pituitary gland to release more LH and FSH. High LH after menopause is normal.
Can stress affect LH levels?
Yes. Chronic stress, excessive exercise, illness, and poor nutrition can suppress reproductive hormones, including LH. In some cases this can lead to missed periods or fertility problems.