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Lactate Dehydrogenase (LDH) Activity in Serum/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 cell damage or disease processes in various organs.

Quick summary

["LDH helps doctors identify potential tissue injury or metabolic conditions."]

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

Key facts at a glance

LOINC
81430-1
Short code
LDH DiafP L to P-cCnc
Synonyms
LDH DiafP 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
SNOMED
394971007
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 commonly used to diagnose or monitor conditions affecting the heart, liver, kidneys, lungs, muscles, and blood cells. Elevated levels may suggest damage to these tissues, while certain disorders like anemia or infections can also influence results.

Common Conditions Monitored

High LDH levels may be linked to conditions such as heart attacks, liver disease, kidney problems, certain cancers, or severe infections. Low levels are less common but could indicate specific metabolic or genetic 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 enzymatic method. Results are reported in units per liter (U/L) or other standardized units.

What Does a High or Low LDH Level Mean?

Elevated LDH can signal widespread tissue damage, but it’s often part of a broader evaluation. For example, heart attack patients may have elevated LDH within days of the event. Low LDH is rare and may require further investigation to rule out underlying causes.

Reference range

Adult: 140-280 U/LN/A

Specimen: serum

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

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, or signs of organ damage (e.g., jaundice for the liver). It may also be part of routine monitoring for conditions like cancer or blood disorders.
What do my LDH results mean for my health?
Results alone don’t diagnose a condition—they’re part of a picture. Elevated LDH often points to tissue injury, but your doctor will consider your symptoms, medical history, and other test results to interpret findings accurately.
Can lifestyle changes affect LDH levels?
Yes, certain activities (like intense exercise) or medical treatments (e.g., chemotherapy) can temporarily raise LDH. However, diet or daily habits usually don’t have a significant impact unless they cause underlying tissue stress.
  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