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Lactate Dehydrogenase (LDH) Activity in Serum

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

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which helps your body convert lactic acid into energy. It’s often checked to assess cell damage or metabolic health.

Quick summary

["LDH helps diagnose conditions affecting cells or energy production in your body."]

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

Key facts at a glance

LOINC
2529-6
Short code
LDH Fld-cCnc
Synonyms
LDH Fld-cCnc
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

Why Is This Test Done?

Doctors may order LDH testing to evaluate symptoms like fatigue, muscle weakness, or unexplained pain. It can also help identify conditions such as heart attacks, liver disease, red blood cell disorders, or infections.

What Does a Result Mean?

Higher-than-normal LDH levels may suggest damage to cells in organs like the heart, liver, or muscles. Lower levels might indicate certain blood disorders or other metabolic issues. Your results will be interpreted by your healthcare provider based on your overall health and symptoms.

Common Conditions Monitored

LDH is commonly used alongside other tests to monitor conditions like myocardial infarction (heart attack), hemolytic anemia (red blood cell destruction), liver disease, or muscle injuries.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The blood is processed to separate serum (the liquid part after clotting), which is then sent to a lab for testing. LDH activity is measured using an enzymatic method.

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 Serum

Frequently asked questions

What causes LDH levels to rise?
LDH levels can increase due to damage to cells in organs like the heart, liver, kidneys, or muscles. Conditions such as heart attacks, liver disease, infections, or certain cancers may also lead to higher levels. Stress, exercise, or certain medications can temporarily affect LDH as well.
What if my LDH test result is abnormal?
If your LDH result is higher than expected, your healthcare provider will review your symptoms, medical history, and other test results to determine the cause. They may recommend additional tests or treatments to address the underlying issue.
Can LDH levels be affected by diet or supplements?
Dietary factors or supplements alone typically do not significantly alter LDH levels. However, certain medications (like some chemotherapy drugs or statins) or chronic conditions may influence results. Always discuss any medications or supplements with your provider before testing.
  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