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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in converting lactate to pyruvate during energy production in cells. LDH levels can help identify conditions affecting cell damage or metabolism.

Quick summary

["LDH helps diagnose tissue damage or metabolic issues by measuring enzyme activity in your blood."]

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

Key facts at a glance

LOINC
31016-9
Short code
L-amphet MFr Ur
Synonyms
L-amphet MFr Ur
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

What Is LDH Used For?

LDH is primarily used to detect and monitor conditions that cause damage to cells, such as heart attacks, muscle injuries, liver disease, or certain cancers. It can also be checked during pregnancy to assess for complications like preeclampsia.

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 automated enzymatic method. No special preparation is needed, but fasting may be advised depending on your specific test order.

What Are Common Causes of Abnormal Results?

Elevated LDH levels may occur due to conditions like heart attacks, liver disease, muscle injuries, infections, or certain cancers. Lower-than-normal levels are less common but can sometimes be seen in rare genetic disorders or severe malnutrition.

How Are Results Interpreted?

Results are reported in units per liter (U/L) or milliliters per liter (mU/L), but exact reference ranges vary by lab. Your healthcare provider will interpret your results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

LDH is a sensitive marker for cell damage across multiple organ systems. While it doesn’t pinpoint the exact cause of damage, elevated levels often prompt further testing for conditions like myocardial infarction, hepatitis, or hematologic malignancies. LDH can also be used as a prognostic tool in some diseases.

Short name

LDH Activity

Frequently asked questions

Why might my LDH test be ordered?
Your doctor may order an LDH test to investigate symptoms like chest pain, fatigue, unexplained muscle weakness, or liver-related issues. It’s also sometimes used during pregnancy to monitor for complications or as part of routine cancer screenings.
What do I need to do before my LDH test?
No special preparation is typically required, but you may be asked to fast for 8–12 hours before the test if it’s part of a metabolic study. Always follow your healthcare provider’s instructions.
Can LDH levels change with diet or exercise?
Yes, physical activity can temporarily increase LDH levels due to muscle damage. Certain foods or supplements may also affect enzyme activity, but these effects are usually short-term. Your results should be interpreted with your overall health in mind.
  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