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Serum Creatinine Phosphokinase (CPK) Isoenzyme Analysis (MB Fraction)

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

This test measures the MB (myocardial-binding) fraction of Creatine Phosphokinase (CPK), an enzyme found primarily in heart muscle. It helps assess heart tissue damage or injury.

Quick summary

["The CPK-MB test can identify heart-related issues, such as a heart attack or muscle strain."]

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

Key facts at a glance

LOINC
47910-5
Short code
GH 30M p betaxolol+Gc SerPl-aCnc
Synonyms
GH 30M p betaxolol+Gc SerPl-aCnc
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

What Is CPK-MB Used For?

CPK-MB is often used to diagnose or monitor conditions affecting heart muscle, such as a heart attack (myocardial infarction). It can also help determine the extent of heart damage or guide treatment decisions.

How Is CPK-MB Different from Other CPK Tests?

Unlike total CPK (which includes all CPK fractions), CPK-MB specifically targets the MB fraction, which is more specific to heart tissue. This helps distinguish heart-related issues from muscle damage elsewhere in the body.

What Does an Elevated CPK-MB Level Indicate?

High levels of CPK-MB in the blood may signal recent or ongoing heart muscle damage, such as from a heart attack, heart surgery, or severe heart strain. However, results alone should not be interpreted without clinical context.

How Is CPK-MB Tested?

A blood sample is drawn, typically from your arm, and sent to a lab. The lab measures the concentration of CPK-MB in your serum. Results are usually available within 24 to 48 hours.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CPK-MB plays a key role in diagnosing and managing cardiac conditions. Elevated levels are strongly associated with myocardial infarction (heart attack) and can help confirm or rule out heart damage. It is often used alongside other tests, such as troponin, to assess heart injury.

Short name

CPK-MB (Serum)

Frequently asked questions

Why might my doctor order a CPK-MB test?
Your doctor may recommend this test if you’ve experienced chest pain, heart symptoms, or if you’re undergoing heart-related procedures (e.g., surgery, stress tests). It helps evaluate whether your heart tissue has been damaged.
What are the typical reference ranges for CPK-MB?
Reference ranges vary by lab and individual factors. A normal result does not guarantee no heart damage, while an elevated result warrants further medical evaluation.
Can CPK-MB levels change with physical activity?
Yes, exercise can temporarily raise CPK-MB levels, but if you’ve had recent heart symptoms, your doctor may still monitor it to assess potential heart strain.
  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