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Lactate Dehydrogenase (LDH) Activity in Serum

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

This test measures the activity of an enzyme called lactate dehydrogenase (LDH) found in many parts of the body, including heart, liver, muscles, and red blood cells. It helps assess damage to these tissues.

Quick summary

["LDH helps doctors identify potential tissue injury or disease."]

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

Key facts at a glance

LOINC
68452-2
Short code
LDH Snv P to L-cCnc
Synonyms
LDH Snv P to L-cCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
reaction-pyruvate-to-lactate
CPT
85610
SNOMED
396252006
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order an LDH test to check for conditions that affect organs like the heart, liver, or muscles. It can also be used to monitor certain cancers, infections, or blood disorders. Sometimes, it’s part of a broader evaluation for unexplained symptoms like fatigue, chest pain, or unexplained bruising.

Common Conditions Monitored

High LDH levels may suggest damage to cells in organs such as the heart (myocardial infarction), liver (hepatitis), or muscles (myopathy). It can also be elevated in conditions like certain cancers (e.g., lymphoma), infections, or blood disorders like hemolytic anemia.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for a few hours before the test if your doctor specifies it, but this is rare for LDH. Bring any medications or supplements you’re taking to your appointment.

What Happens During the Test?

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

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: fluid

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Serum

Frequently asked questions

What does an abnormal LDH result mean?
An elevated LDH result may indicate tissue damage or disease, but it doesn’t always mean a serious condition. Your doctor will review your test results alongside other symptoms, medical history, and tests to determine the cause. For example, mild elevations might be due to muscle activity or certain medications.
How long does it take to get the results?
LDH test results are typically available within 1 to 3 business days, depending on your lab’s processing times. Your doctor will contact you once the results are ready, usually through your healthcare provider’s office or electronic health records.
Can lifestyle changes affect LDH levels?
Yes, certain lifestyle factors can influence LDH levels. Heavy exercise or muscle strain may temporarily raise LDH, as can certain medications (e.g., some chemotherapy drugs or blood thinners). If you suspect lifestyle changes are affecting your results, discuss them with your doctor.
  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