Lactate Dehydrogenase Isoenzyme Activity (Serum/Plasma) – Electrophoresis
This test measures the activity levels of different isoenzymes of lactate dehydrogenase (LDH), an enzyme involved in energy production in cells. It helps identify which specific isoenzyme is elevated, which can indicate certain tissue injuries or conditions.
["Elevated isoenzyme patterns may signal specific types of tissue damage or disease."]
Key facts at a glance
- LOINC
- 51517-1
- Short code
- LDH4 CFr Prt Elph
- Synonyms
- LDH4 CFr Prt Elph
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 140
- Ref high
- 280
- Critical range
- 7.2 N/A – 7.6 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- electrophoresis
- 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
Why This Test Is Done
Doctors may order this test to investigate symptoms such as muscle weakness, chest pain, or unexplained fatigue. It can also help diagnose conditions like heart attack (myocardial infarction), liver disease, red blood cell disorders, or certain cancers. The specific isoenzyme patterns can provide clues about the type of tissue affected.
How the Test Works
The test uses serum or plasma collected from a blood sample. The sample is separated into different fractions based on the electrical charge of the LDH isoenzymes, allowing for their individual measurement. This process helps determine which isoenzyme is predominantly active.
Sample Collection and Preparation
A blood sample is drawn from a vein, typically in the arm. The blood is then processed to separate the serum or plasma for testing. This sample is sent to a laboratory where electrophoresis is performed to analyze the isoenzyme activity levels.
Possible Results and Interpretation
The results show the relative activity of different LDH isoenzymes, often expressed as a percentage or ratio. For example, elevated LDH-1 (heart muscle) may suggest heart damage, while elevated LDH-5 (liver or muscle) could indicate liver disease or muscle injury. Interpretation requires clinical correlation with patient symptoms and history.
Reference range
Adult: 140-280 U/LN/A
No special preparation required. Inform provider of any chest pain or symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated LDH isoenzyme levels can indicate tissue damage or disease in various organs, including the heart, liver, muscles, kidneys, or red blood cells. LDH-1 is often associated with heart attacks, while LDH-5 is linked to muscle or liver conditions. Monitoring isoenzyme patterns helps guide treatment decisions and assess disease progression.
Short name
LDH Isoenzyme Profile
Frequently asked questions
What does an elevated LDH isoenzyme mean?
How long does it take to get the results?
Can I eat or drink before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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