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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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

This test measures the activity level of lactate dehydrogenase, an enzyme found in many tissues that helps convert lactate to pyruvate during energy production. It can help identify conditions affecting cell damage or metabolism.

Quick summary

["LDH helps diagnose conditions linked to tissue injury or metabolic changes."]

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

Key facts at a glance

LOINC
51514-8
Short code
LDH3 CFr Plr Elph
Synonyms
LDH3 CFr Plr Elph
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Ref low
140
Ref high
280
Critical range
7.2 N/A – 7.6 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
electrophoresis
CPT
83615
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?

Doctors may order LDH testing to evaluate symptoms such as muscle weakness, chest pain, or unexplained fatigue. It can also help detect conditions like heart attacks, liver disease, red blood cell disorders, or certain cancers, where elevated LDH levels often appear.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis using an enzymatic method to measure LDH activity in your serum or plasma.

What Are Possible Results?

Results are reported as the activity level of LDH, measured in units per liter (U/L). Higher-than-normal levels may indicate tissue damage or metabolic issues, while lower levels might suggest certain metabolic or genetic conditions.

What Does It Mean If My Results Are Abnormal?

Elevated LDH levels can signal conditions such as heart disease, liver problems, muscle injuries, anemia, or infections. Low levels may be seen in rare genetic disorders or certain metabolic conditions. Always discuss results with your healthcare provider.

Reference range

Adult: 140-280 U/LN/A

Specimen: fluid

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Activity

Frequently asked questions

What does a high LDH level typically indicate?
A high LDH level may suggest damage to cells in organs like the heart, liver, or muscles, or conditions affecting red blood cells, such as anemia or infections. It can also be part of monitoring for certain cancers.
How long does it take to get my LDH test results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing schedule. Your healthcare provider will contact you once results are ready.
Can lifestyle changes affect LDH levels?
While LDH levels are influenced by tissue damage or metabolic processes, lifestyle factors like exercise intensity or diet may indirectly affect certain conditions linked to LDH (e.g., muscle injury or metabolic health). Always follow your doctor’s guidance for interpretation.
  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