Lactate Dehydrogenase (LDH) Isoenzyme Profile (Serum/Plasma)
This test measures different forms (isoenzymes) of the enzyme lactate dehydrogenase (LDH) in your blood. Each isoenzyme can help identify where in your body damage or disease may be occurring.
["LDH isoenzyme testing helps pinpoint potential tissue injury or disease beyond general LDH levels alone."]
Key facts at a glance
- LOINC
- 2536-1
- Short code
- LDH1 CFr SerPl Elph
- Synonyms
- LDH1 CFr SerPl 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 like muscle pain, heart problems, liver issues, or red blood cell disorders. It can also help diagnose conditions such as heart attacks, muscle injuries, or certain cancers.
Your blood sample is analyzed to separate and measure different LDH isoenzymes using electrophoresis. This method helps identify which isoenzyme is elevated, which can indicate the specific tissue affected.
A blood sample is taken from a vein in your arm. The sample is then sent to a lab where it undergoes electrophoresis to separate LDH isoenzymes. Results are reported as a profile of different isoenzyme levels.
What to Expect Before the Test
No special preparation is needed, but you may want to avoid strenuous exercise or consuming certain foods (like red meat) 24 hours before the test if your doctor advises it.
Interpreting results involves looking at which isoenzymes are elevated. For example, certain patterns may suggest heart muscle damage, liver disease, or red blood cell breakdown. Your doctor will discuss these findings with you.
Elevated LDH isoenzymes can signal tissue damage across many organs, but the specific isoenzyme pattern helps narrow down the possible cause. Your doctor will correlate these results with your symptoms and medical 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.
◆Associated findings1
Short name
LDH Isoenzyme Profile
Frequently asked questions
What does an elevated LDH isoenzyme profile indicate?
Do I need to fast before this test?
How long will it take to get my results?
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