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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 assess cell damage or health in various tissues.

Quick summary

["LDH helps diagnose conditions affecting muscle, liver, heart, or red blood cells."]

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

Key facts at a glance

LOINC
60019-7
Short code
LDH Pcar L to P-cCnc
Synonyms
LDH Pcar L to P-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
Method
reaction-lactate-to-pyruvate
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 to identify damage in organs like the heart (e.g., after a heart attack), liver, or muscle injuries. It can also help monitor conditions like anemia or certain cancers.

Why Might You Need This Test?

Your doctor may order LDH if you have symptoms like chest pain, unexplained fatigue, or signs of organ damage. It’s also used in follow-up care for conditions like heart disease, liver disease, or blood disorders.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where LDH activity is measured using an automated test that detects enzyme levels.

What Are Common Causes of Elevated LDH?

High LDH levels may suggest conditions like heart attacks, liver disease, muscle injuries, or certain cancers. Low levels are less common but could indicate certain metabolic or genetic disorders.

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 Activity

Frequently asked questions

What does a normal LDH level mean?
A normal LDH level doesn’t mean you’re healthy—it just means your LDH activity is within the expected range for your age and health. Your doctor will consider your symptoms, other test results, and medical history to interpret the results.
Can LDH levels change over time?
Yes, LDH levels can fluctuate depending on your health status, medications, or underlying conditions. If your levels are elevated, your doctor may retest to monitor changes over time.
Does diet or exercise affect LDH levels?
Exercise can temporarily raise LDH levels, especially in muscle-heavy activities. Certain foods or medications may also influence results, so it’s important to follow your doctor’s instructions for fasting or timing the test.
  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