Muscle Creatine Phosphokinase (CPK) Isoenzyme: Myocardial (MB) Fraction
This test measures a specific form of creatine phosphokinase (CPK), an enzyme found mostly in heart and muscle tissues. Elevated levels may signal heart muscle damage.
["Elevated MB-CPK can indicate recent heart injury, helping doctors assess heart attack risk or other cardiac conditions."]
Key facts at a glance
- LOINC
- 98684-4
- Short code
- Motor NC Pnl L fibular n
- Synonyms
- Motor NC Pnl L fibular n
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 Matters in Heart Health
CPK is an enzyme that helps cells produce energy. In the heart, it exists in different forms (isoenzymes), including the MB form, which is released into the bloodstream when heart muscle cells are damaged. This test specifically measures the MB fraction to detect heart injury, such as during a heart attack.
When Might You Need This Test?
Your doctor may order an MB-CPK test if you experience symptoms like chest pain, shortness of breath, or other signs of heart trouble. It’s also used after a suspected heart attack to monitor recovery or check for complications.
What to Expect Before the Test
You’ll likely have a simple blood draw from a vein in your arm. No special preparation is needed, but inform your doctor about any medications or recent injuries, especially to the heart or muscles.
What the Results Mean
Results show the amount of MB-CPK in your blood. Higher than normal levels suggest recent heart damage. Your doctor will compare these results with your symptoms and other tests to diagnose or guide treatment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated MB-CPK is a key marker for myocardial infarction (heart attack) or other cardiac events. It helps doctors confirm heart damage, assess severity, and plan treatment, such as medications or procedures to restore blood flow or repair damaged tissue.
Short name
MB-CPK (Myocardial CPK)
Frequently asked questions
What causes elevated MB-CPK levels?
How quickly do results return?
Can lifestyle changes lower MB-CPK levels?
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