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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in energy production in cells. It can help identify conditions affecting muscle, liver, heart, or red blood cells.

Quick summary

["LDH helps diagnose damage to organs or tissues and assesses certain blood disorders."]

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

Key facts at a glance

LOINC
60018-9
Short code
LDH Pcar P to L-cCnc
Synonyms
LDH Pcar P to L-cCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
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
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 blood tests to evaluate conditions like heart attacks, liver disease, muscle injuries, or certain cancers. It can also help monitor how well treatments are working for conditions like anemia or infections.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab where LDH activity is measured using a specialized test that detects how quickly the enzyme converts lactate to pyruvate.

What Does a High or Low LDH Level Mean?

Elevated LDH levels may indicate damage to cells in organs like the heart, liver, or muscle, or conditions such as anemia, certain cancers, or infections. Low LDH levels are less common and may suggest certain genetic disorders or specific medical treatments.

Common Conditions Linked to LDH Levels

High LDH is frequently seen in emergencies like heart attacks, severe muscle injuries, or liver problems. Chronic conditions like anemia or certain cancers can also raise LDH levels over time.

Reference range

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

Specimen: serum

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 Activity

Frequently asked questions

Why might my LDH test be ordered?
Your doctor may order an LDH test if you have symptoms like chest pain, unexplained fatigue, unexplained muscle weakness, or if they suspect a condition like a heart attack, liver disease, or blood disorder. It can also be part of routine monitoring for certain chronic illnesses.
What are the typical reference ranges for LDH?
Reference ranges can vary by lab and may not include a single number for everyone. Your results will be compared to a range based on your age, sex, and overall health. Your doctor will discuss what your specific results mean for you.
Do I need to prepare for this test?
No special preparation is needed for an LDH test. You can eat and drink normally before the blood draw, but avoid heavy exercise or alcohol for a few hours beforehand if advised by 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