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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

Published: August 9, 2026Updated: August 17, 2026

This test measures the level of lactate dehydrogenase, an enzyme found in many tissues, including the heart, liver, muscles, and red blood cells. It helps identify conditions affecting these organs.

Quick summary

["LDH can signal damage to organs or tissues, aiding in diagnosing conditions like heart attacks, liver disease, or muscle injuries."]

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

Key facts at a glance

LOINC
41774-1
Short code
XR port Neck Lat
Synonyms
XR port Neck Lat
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-portable
CPT
82553
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 primarily used to detect and monitor damage to cells in various organs. Elevated levels may suggest conditions such as heart attacks (myocardial infarction), liver disease, certain cancers, or muscle injuries. It can also help track the progression or response to treatment in these conditions.

How Is LDH Tested?

The LDH test involves drawing blood from a vein in your arm. The blood sample is then sent to a lab, where it is analyzed to measure the enzyme activity. Results are typically reported in units per liter (U/L), though specific reference ranges can vary by lab.

When Might You Need This Test?

Your healthcare provider may order an LDH test if you have symptoms like chest pain (possible heart attack), unexplained fatigue, jaundice (yellowing of skin/eyes), muscle weakness, or if you have a known condition like liver disease, cancer, or a recent injury.

What Do Results Mean?

Results can vary depending on the context. Generally, higher LDH levels may indicate tissue damage, while lower levels might suggest certain metabolic or genetic conditions. Your doctor will interpret the results in relation to your symptoms and medical history.

Reference range

Adult males: 22-198 U/L; Females: 22-198 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 Activity

Frequently asked questions

Why might my LDH levels be checked regularly if I have a chronic condition like heart disease or cancer?
Regular LDH monitoring helps track changes in your condition. For example, in heart disease, it can help detect early signs of tissue damage. In cancer, it may be used to monitor disease progression or response to treatment by assessing how your body’s cells are functioning.
Can lifestyle changes, such as diet or exercise, affect LDH levels?
Yes, lifestyle factors can influence LDH levels. For instance, intense physical exercise can temporarily raise LDH due to muscle damage. Eating a balanced diet rich in antioxidants may help support overall cellular health, potentially affecting enzyme activity indirectly.
What should I do if my LDH test results are unusually high?
If your LDH levels are elevated, your healthcare provider will review your symptoms, medical history, and other test results to determine the cause. They may recommend further testing or adjustments to your treatment plan based on the 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 17, 2026. · Read our editorial policy