Skip to content

Lactate Dehydrogenase (LDH) Activity in Serum or Plasma

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

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in energy production in cells. It helps evaluate conditions affecting cell damage or metabolism.

Quick summary

["LDH helps diagnose and monitor conditions linked to cell injury or metabolic issues."]

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

Key facts at a glance

LOINC
48225-7
Short code
Cow Milk LR-mCnc
Synonyms
Cow Milk LR-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

What Does LDH Measure?

LDH is an enzyme found in many tissues, including the heart, liver, kidneys, brain, and red blood cells. When cells are damaged, LDH is released into the bloodstream. Different levels of LDH can indicate specific types of tissue injury or disease processes.

Why Is LDH Tested?

Doctors may order an LDH test to investigate symptoms such as chest pain, shortness of breath, abdominal pain, or unexplained fatigue. It can also be used to monitor conditions like heart attacks, liver disease, anemia, or certain cancers.

Common Conditions Affecting LDH Levels

High LDH levels may suggest conditions like heart attacks, liver disease, muscle injuries, or certain blood disorders. Low LDH levels are less common but can occur in rare genetic disorders or severe infections.

How Is the LDH Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab for testing. LDH activity is measured using a specialized test that detects how quickly the enzyme converts lactate to pyruvate.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Test

Frequently asked questions

How is LDH used in diagnosis and treatment?
LDH is often used alongside other tests to confirm or narrow down diagnoses. For example, elevated LDH can help identify heart damage (myocardial infarction) or liver disease, guiding treatment plans like medication adjustments or further testing.
What are the typical reference ranges for LDH?
Reference ranges vary by lab and can depend on factors like age, sex, and overall health. Your doctor will provide your specific results and compare them to your personal baseline.
Can lifestyle changes affect LDH levels?
Yes, certain activities like intense exercise, muscle injuries, or poor nutrition can temporarily raise LDH levels. It’s important to discuss any recent changes or symptoms with your healthcare provider.
  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