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Luteinizing Hormone (LH) – Serum

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of luteinizing hormone (LH) in your blood. LH is a hormone produced by the pituitary gland that plays a key role in reproductive health, including ovulation in women and sperm production in men.

Quick summary

["LH helps regulate your menstrual cycle and fertility."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
103649-0
Short code
LH 10M p GnRH SerPl-aCnc
Synonyms
LH 10M p GnRH SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
1.5
Ref high
9
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83002
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What LH Measures

LH is crucial for triggering ovulation in women and stimulating testosterone production in men. It fluctuates throughout the menstrual cycle and peaks around the time of ovulation. In men, LH supports the production of testosterone by the testes.

Why It’s Ordered

Doctors may order an LH test to evaluate fertility issues, hormone imbalances, or conditions affecting the pituitary gland. It can also help diagnose problems like polycystic ovary syndrome (PCOS) in women or low testosterone in men.

Sample Collection and Preparation

This test requires a blood sample drawn from a vein in your arm. You may be asked to fast for a few hours before the test, depending on your doctor’s instructions. The sample is sent to a lab for analysis.

What to Expect Before the Test

No special preparation is always required, but your doctor may advise you to avoid certain medications or activities. If you’re pregnant or breastfeeding, let your doctor know before the test.

Reference range

Follicular: 1.5-9.0 mIU/mLN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormally high LH levels may indicate conditions like premature ovarian failure in women or pituitary tumors. Low LH levels could suggest hormonal deficiencies, such as hypogonadism, or problems with the hypothalamus or pituitary gland. Monitoring LH levels helps guide treatment for fertility issues or hormone-related disorders.

Short name

LH Test

Frequently asked questions

When might I need an LH test?
You may need an LH test if you’re experiencing infertility, irregular menstrual cycles, low libido, or symptoms like fatigue, weight gain, or hair loss. Doctors may also order it to check for hormonal imbalances or to monitor conditions like PCOS or hypogonadism.
What does an LH test tell me about my health?
An LH test helps assess whether your hormone levels are within a healthy range. High or low LH levels can signal potential issues with your reproductive or endocrine systems, prompting further evaluation by your healthcare provider.
Can LH levels change with age?
Yes, LH levels naturally fluctuate with age and hormonal cycles. In women, LH peaks during ovulation and declines afterward. In men, LH levels tend to decrease slightly with age, though this varies by individual.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy