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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in converting lactate to pyruvate and vice versa. LDH is found in many tissues, including the heart, liver, kidneys, and red blood cells.

Quick summary

["LDH helps diagnose conditions affecting these organs and assesses overall health."]

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

Key facts at a glance

LOINC
53934-6
Short code
LDH Prt/SerPl
Synonyms
LDH Prt/SerPl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
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
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 Is This Test Done?

Your doctor may order an LDH test to check for damage to organs like the heart, liver, or kidneys. It can also help identify conditions such as muscle injuries, certain cancers, or infections. LDH levels can rise when cells break down, releasing the enzyme into the bloodstream.

What Does an LDH Test Tell You?

Elevated LDH levels may suggest tissue damage or disease, but the exact cause depends on which tissues are affected. For example, high levels in the heart could indicate a heart attack, while high levels in the liver might point to hepatitis or cirrhosis.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. You may feel a small pinch when the needle is inserted, but it usually doesn’t cause much discomfort. The sample is then sent to a lab for testing.

What Do My Results Mean?

Your results will be compared to a reference range provided by your healthcare provider. While reference ranges can vary slightly between labs, they help determine if your LDH levels are within normal limits or if further investigation is needed.

Reference range

Adult: 140-280 U/LN/A

Specimen: serum

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: LDH Levels and Health Conditions

Short name

LDH Activity

Frequently asked questions

What Are Common Causes of High LDH Levels?
High LDH levels can be caused by conditions such as heart attacks, liver disease, kidney problems, muscle injuries, certain cancers (like lymphoma or leukemia), infections, or blood disorders. Low LDH levels are less common and may indicate certain genetic disorders or liver diseases.
How Often Should I Get This Test?
Your doctor will determine how often you need an LDH test based on your health history, symptoms, and other test results. Regular monitoring may be recommended if you have a known condition that affects LDH levels, such as heart disease or cancer.
Can I Take Anything Before the Test?
No special preparation is usually needed for an LDH test. However, if you are on certain medications or have specific health conditions, inform your healthcare provider before the test.
  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