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Lactate Dehydrogenase (LDH) Activity in Serum or Plasma

Published: August 9, 2026Updated: August 17, 2026

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in energy production in cells. LDH levels can help identify conditions affecting tissues, such as damage or disease.

Quick summary

["LDH helps doctors assess tissue health and potential damage."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
109606-4
Short code
LDH Msmt Plr
Synonyms
LDH Msmt Plr
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Ref low
140
Ref high
280
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83615
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What Does LDH Measure?

LDH is an enzyme found in many tissues throughout the body, including the heart, liver, kidneys, muscles, and red blood cells. When cells are damaged, LDH is released into the bloodstream. Measuring LDH activity helps determine the extent of tissue injury or disease activity.

Why Might You Need This Test?

Doctors may order LDH testing to investigate symptoms like chest pain, fatigue, muscle weakness, or unexplained lab abnormalities. It’s also used in monitoring conditions such as heart attacks, liver disease, anemia, and certain cancers.

Common Conditions Monitored

High LDH levels may suggest conditions like muscle injuries, heart attacks, liver disease, or certain blood disorders. Low levels are less common but could indicate conditions like severe anemia or certain metabolic disorders.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for testing LDH activity using an enzymatic method that measures how quickly the enzyme converts lactate to pyruvate.

Reference range

Adult: 140-280 U/LN/A

Specimen: fluid

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

LDH Activity

Frequently asked questions

Why do doctors check LDH levels?
Doctors use LDH to assess tissue damage or disease progression. For example, elevated LDH can signal heart muscle damage (myocardial infarction), liver disease, or muscle disorders. It’s also part of a broader evaluation for conditions like leukemia or other cancers.
What do my LDH results mean?
Results are compared to a reference range for your age and health status. While elevated LDH often points to tissue injury, doctors consider other test results and symptoms to determine the cause. A single high result doesn’t always mean a serious condition—further testing may be needed.
Can lifestyle changes affect LDH levels?
Yes, certain activities like intense exercise, muscle strain, or poor nutrition may temporarily raise LDH levels. However, if you have persistent high levels, your doctor may recommend lifestyle adjustments or additional tests to understand the cause.
  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 17, 2026. · Read our editorial policy