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Luteinizing Hormone (LH) in Serum/Plasma

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

This test measures the level of luteinizing hormone (LH), a hormone produced by the pituitary gland that plays a key role in reproductive health.

Quick summary

["LH helps regulate ovulation in women and sperm production in men."]

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

Key facts at a glance

LOINC
55501-1
Short code
LH 4h p chal SerPl-aCnc
Synonyms
LH 4h p chal 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

Why This Test Might Be Ordered

Your doctor may recommend an LH test to evaluate fertility issues, check for hormonal imbalances, monitor conditions like polycystic ovary syndrome (PCOS), or assess pituitary gland function. It can also be part of routine testing for reproductive health or thyroid disorders.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Women may be advised to test during a specific phase of their menstrual cycle if fertility is being evaluated.

How the Test Works

A small blood sample is taken from a vein in your arm. The sample is sent to a lab, where it is analyzed using an immunoassay method to measure LH levels. The results help determine hormone activity in your body.

What the Results Mean

Results are typically reported in international units per liter (IU/L). Higher than expected levels may indicate conditions like ovarian hyperstimulation or certain tumors, while lower levels could suggest pituitary dysfunction or other hormonal disorders.

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.

◆Associated findings1

Short name

LH Test

Frequently asked questions

What causes LH levels to be too high?
High LH levels can result from conditions like ovarian cysts, polycystic ovary syndrome (PCOS), or certain tumors affecting the pituitary or ovaries. Stress, thyroid disorders, or medications may also influence hormone levels.
What causes LH levels to be too low?
Low LH levels may occur due to pituitary gland disorders (such as hypopituitarism), primary ovarian insufficiency, or conditions affecting hormone production in the hypothalamus. Rarely, genetic factors or certain medications can contribute.
How often should I get this test?
The frequency depends on your health needs. If you're undergoing fertility treatment, your doctor may recommend testing every few months. Otherwise, it’s often checked as part of routine evaluations for hormonal or reproductive health concerns.
  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