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Lactate Dehydrogenase (LDH) Activity in Serum or Plasma

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["LDH levels can signal tissue damage or metabolic issues."]

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

Key facts at a glance

LOINC
109701-3
Short code
LDH Msmt Prt
Synonyms
LDH Msmt Prt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
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
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 Is LDH Used For?

LDH is often checked alongside other tests like creatine kinase (CK) or troponin when evaluating conditions such as heart attacks, muscle injuries, liver disease, or certain cancers. It can also help diagnose infections or blood disorders.

How Is LDH Tested?

A blood sample is taken, and the enzyme activity is measured using an automated laboratory method. Results are reported in units per liter (U/L) or other standardized units.

When Might You Need an LDH Test?

Your doctor may order an LDH test if you have symptoms like chest pain, muscle weakness, fatigue, or unexplained bruising, or if you have a known condition like heart disease, liver problems, or cancer.

What Do Results Mean?

Elevated LDH levels may indicate damaged or stressed cells, but interpretation depends on your overall health and other test results. Normal ranges vary by lab and may not apply to everyone.

Reference range

Adult: 140-280 U/LN/A

Specimen: serum

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

Why might my LDH test be ordered?
Your doctor may recommend it to investigate symptoms like unexplained fatigue, muscle pain, or organ-related issues, or as part of a broader evaluation for conditions like heart disease, infections, or blood disorders.
What do my LDH results mean?
Results alone don’t provide a diagnosis. Your doctor will compare them to your symptoms, other test results, and medical history to determine next steps.
Can lifestyle changes affect LDH levels?
Moderate physical activity or diet may not significantly alter LDH levels, but severe muscle damage (e.g., from intense exercise or injury) could temporarily raise them.
  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