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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, which is important for energy production.

Quick summary

["LDH levels can help diagnose conditions affecting cells, such as heart attacks, muscle injuries, or certain cancers."]

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

Key facts at a glance

LOINC
104814-9
Short code
LDH1 CFr Ur
Synonyms
LDH1 CFr Ur
Category
chemistry
Sample
urine
Container
Sterile urine container
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
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order an LDH test to check for damage to cells in your body, such as those in your heart, liver, muscles, or lungs. It can also help identify conditions like anemia, infections, or certain types of cancer.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, but this isn’t always required. Bring any medications you’re currently taking, as some may affect results. Avoid strenuous exercise 24 hours before testing.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause long-lasting discomfort. The blood sample is then sent to a lab for testing.

What the Results Mean

Higher than normal LDH levels may indicate cell damage or disease, but results alone don’t diagnose a condition. Your doctor will review your full medical history and other test results for comparison.

Reference range

Adult: 140-280 U/LN/A

Specimen: urine

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 causes elevated LDH levels?
Elevated LDH levels can be caused by conditions such as heart attacks (myocardial infarction), liver disease, muscle injuries (like from strenuous exercise or trauma), certain cancers (like lymphoma or leukemia), anemia, or infections.
What causes low LDH levels?
Low LDH levels are less common and may occur in certain genetic disorders or conditions affecting red blood cell production, such as severe hemolytic anemia. Your doctor will assess the context and other test results.
How often should LDH levels be checked?
LDH levels may be checked periodically if you have ongoing health conditions like heart disease, liver disease, or cancer. Your doctor will determine the need for follow-up testing based on your specific situation.
  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