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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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

This test measures the activity level of the enzyme lactate dehydrogenase (LDH) in your blood. LDH helps convert lactate to pyruvate and is found in many tissues, including the heart, liver, muscles, and red blood cells.

Quick summary

["LDH helps diagnose and monitor conditions affecting these organs and tissues."]

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

Key facts at a glance

LOINC
60022-1
Short code
LDH Plr L to P-cCnc
Synonyms
LDH Plr L to P-cCnc
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
Method
reaction-lactate-to-pyruvate
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 that plays a role in energy production in your cells. Elevated levels can indicate damage to cells, as LDH leaks into the bloodstream when tissues are injured or inflamed. Different types of LDH (isoenzymes) can help pinpoint which organs or tissues may be affected.

Why Might You Need This Test?

Your doctor may order an LDH test to investigate symptoms like chest pain, muscle weakness, fatigue, or unexplained lab abnormalities. It’s also used to monitor conditions such as heart attacks, liver disease, muscle disorders, anemia, and certain cancers.

Common Conditions Linked to LDH Levels

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

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where LDH activity is measured using an enzymatic method. The result is reported as the enzyme’s activity level, often compared to a reference range for your age and health status.

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.

◆Associated findings1

Short name

LDH Activity

Frequently asked questions

What Causes Elevated LDH Levels?
Elevated LDH levels can result from tissue damage or inflammation in organs like the heart, liver, kidneys, lungs, or muscles. It may also be linked to certain cancers, infections, or blood disorders. Your doctor will consider your symptoms, medical history, and other test results to interpret the results.
What Causes Low LDH Levels?
Low LDH levels are rare but can occur in severe anemia, certain metabolic disorders, or during pregnancy. If your levels are low, your doctor may investigate underlying causes like vitamin deficiencies or genetic conditions.
How Often Should I Get This Test?
The frequency of LDH testing depends on your health condition and symptoms. Your doctor may recommend regular monitoring if you have a known risk factor (e.g., heart disease, liver issues) or if you’re undergoing treatment for a condition that affects LDH levels.
  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