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Serum/plasma concentration of lactate dehydrogenase (LDH) measured by immunoassay

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

Lactate dehydrogenase (LDH) is an enzyme found in many cells throughout your body. It helps break down sugars for energy. Your blood test measures how much LDH is in your serum or plasma.

Quick summary

["LDH helps doctors assess cell damage or health in organs like the heart, liver, or muscles."]

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

Key facts at a glance

LOINC
30151-5
Short code
LA TSH SerPl-aCnc
Synonyms
LA TSH SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.4
Ref high
4
Critical range
0.1 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84443
SNOMED
301343003
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 levels can help diagnose conditions affecting organs, such as heart attacks, liver disease, or certain cancers. It may also be checked after trauma or surgery to monitor for complications.

When Might You Need an LDH Test?

Your doctor may order an LDH test if you have symptoms like chest pain, unexplained fatigue, jaundice (yellow skin), or if they suspect organ damage. It’s sometimes included in broader tests for conditions like anemia or infections.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then processed to separate serum or plasma for testing. The immunoassay method detects LDH levels with high accuracy.

What Do Results Mean?

Elevated LDH levels may indicate damage to cells in organs, but results alone don’t confirm a diagnosis. Your doctor will review them alongside other symptoms and tests.

Reference range

Adult: 0.4-4.0 mIU/LN/A

Specimen: serum

Take your thyroid medication after the blood draw if applicable. No fasting required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Level

Frequently asked questions

Why might my LDH test be ordered if I feel fine?
Your doctor may order it as part of a routine checkup, to investigate unexplained symptoms, or to monitor a known condition. LDH can also be elevated in mild conditions like infections or muscle strain, so results are always reviewed with your full medical picture.
Can lifestyle changes affect LDH levels?
Yes, factors like intense exercise, certain medications, or chronic illnesses (e.g., anemia) can influence LDH levels. However, lifestyle changes alone won’t change the test result unless they directly impact organ health.
What if my LDH level is higher than expected?
If your LDH level is elevated, your doctor will discuss possible causes with you, such as organ damage or disease. Follow-up tests or additional questions may be needed to determine the next steps.
  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