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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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

This test measures the activity of an enzyme called lactate dehydrogenase (LDH), which helps your body convert lactate into energy. LDH is found in many tissues, including the heart, liver, kidneys, and red blood cells.

Quick summary

["LDH helps diagnose conditions affecting these organs and assesses overall health."]

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

Key facts at a glance

LOINC
60023-9
Short code
LDH CSF P to L-cCnc
Synonyms
LDH CSF P to L-cCnc
Category
chemistry
Sample
csf
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
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order LDH testing to investigate symptoms like fatigue, chest pain, or unexplained muscle weakness. It’s also used to monitor conditions such as heart attacks, liver disease, muscle injuries, or certain cancers.

What Does the Test Involve?

You’ll provide a blood sample (either serum or plasma) through a simple vein puncture. The lab then measures how much LDH is present in your blood.

What to Expect Before or After the Test

No special preparation is needed, but inform your doctor about any medications or recent illnesses. After the draw, you may feel slight bruising or discomfort at the site, which should resolve quickly.

Common Conditions Linked to LDH Levels

High LDH levels may signal damage to organs like the heart, liver, or muscles. Low levels are less common but could indicate certain blood disorders or severe infections.

Reference range

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

Specimen: csf

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.

LDH is a sensitive marker for tissue injury across multiple organ systems. Elevated levels often prompt further testing for underlying causes, such as myocardial infarction, hepatitis, or metabolic disorders.

Short name

LDH Activity

Frequently asked questions

What causes LDH levels to be high?
High LDH levels can result from tissue damage in organs like the heart, liver, kidneys, or muscles. It may also appear in conditions like anemia, certain cancers, or infections.
What causes LDH levels to be low?
Low LDH levels are rare but can occur with severe blood disorders (e.g., severe anemia) or extreme infections (e.g., sepsis). Your doctor will review your full clinical picture to interpret results.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on lab processing times. Follow up with your healthcare provider to discuss findings.
  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