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: Luteinizing Hormone, Serum or Plasma, by Immunoassay

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

: This test measures the level of luteinizing hormone (LH), a hormone made by the pituitary gland that helps control the menstrual cycle and ovulation in women and testosterone production in men.

Quick summary

[": LH testing helps evaluate fertility, menstrual problems, and pituitary or reproductive hormone function."]

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

Key facts at a glance

LOINC
57107-5
Short code
LH 10M pre GnRH SerPl-aCnc
Synonyms
LH 10M pre 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 Is Luteinizing Hormone?

: LH is a hormone produced by the pituitary gland, a small gland at the base of the brain. In women, it surges mid-cycle and triggers ovulation; in men, it signals the testes to make testosterone. LH levels rise and fall in patterns, so timing of the sample can matter.

: How the Test Is Done

: A blood sample is drawn from a vein in your arm. Your healthcare provider may ask you to collect the sample at a particular point in your menstrual cycle or time of day, depending on what is being evaluated. The sample is sent to the laboratory for immunoassay measurement.

: What the Results Can Indicate

: Results are interpreted alongside your symptoms, age, sex, and other hormone tests. High or low LH can point to issues with the pituitary gland, ovaries, or testes, but results alone do not diagnose a condition. Your provider will explain what your values mean in your specific situation.

: Preparing for the Test

: Follow any instructions your provider gives about timing, fasting, or medications. Tell your care team about hormone medicines, fertility treatments, or supplements you take, because some can affect results. Do not stop prescribed medicines without talking to your provider first.

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.

: LH testing is used to investigate infertility, irregular or absent periods, suspected pituitary disorders, and delayed or early puberty. In fertility care it can help time ovulation or support treatment decisions. Because LH is released in pulses and changes across the cycle, a single value is rarely meaningful on its own, and results should always be interpreted with the full clinical picture and other hormone measurements.

Short name

: LH

Frequently asked questions

: Does an abnormal LH result mean I have a fertility problem?
: Not necessarily. LH is only one part of a complex hormonal system. Abnormal values can reflect timing of the sample or other factors, so results must be interpreted with your symptoms and additional tests.
: Do I need to fast before an LH blood test?
: Fasting is usually not required, but your provider may give specific instructions depending on what else is being tested at the same time. Follow the directions you are given.
: Can my menstrual cycle affect the result?
: Yes. LH levels normally change across the menstrual cycle, so the day of testing can influence results. Your provider may time the test to a specific cycle day for the most useful information. {"slug":"lh10mpregnrhserplacnc","decoded":"Luteinizing Hormone, Serum or Plasma, by Immunoassay","confidence":"medium","note":"The slug is compressed and includes ambiguous fragments (pregnrh, placnc) that may relate to specimen/units or a sample-type qualifier; the test is described generically as an immunoassay of luteinizing hormone in serum or plasma without assuming a specific reference range."}
  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