Creatine Kinase (CK), MB and Total

Also known as: CK-2, CK-MB and Total CK

Clinical Use

Use

MB is the myocardial fraction associated with MI and occurs in certain other states. MB can be used in estimation of infarct size. MB increases have been reported with entities which cause damage to the myocardium, such as myocarditis, some instances of cardiomyopathy, and with extensive rhabdomyolysis, Duchenne muscular dystrophy, malignant hyperthermia, polymyositis, dermatomyositis, mixed connective tissue disease, myoglobinemia, Rocky Mountain spotted fever, Reye syndrome, and rarely in rheumatoid arthritis with high titer RF.2 CK-MB does not generally abruptly rise and fall in such nonacute MI settings, as it does in acute myocardial infarct (AMI).

Special Instructions

Not provided.

Limitations

Triglycerides higher than 300 mg/dL can cause more than 20% loss of CK-MB activity. Factors such as exercise, intramuscular injections, myxedema, grand mal seizures, previous trauma or surgery, and both very early or very late acute myocardial infarction can result in increased total CK but normal CK-MB levels. Also, CK-MB levels might be elevated in marathon runners without myocardial infarction. CK-MB isoenzyme determinations are not typically necessary when the total CK is low, except in elderly patients with low muscle mass where sensitive mass assays could be beneficial. Diagnosis based solely on CK-MB levels can be misleading, hence serial CK isoenzyme analyses and confirmation with LD isoenzymes are recommended.

Test Details

Methodology

Automated Analyzer (Clinical Chemistry)

Biomarkers

LOINC Codes

Order Codes

13969-1 - CK MB SerPl-mCnc
2157-6 - CK SerPl-cCnc

Result Codes

2157-6 - CK SerPl-cCnc
13969-1 - CK MB SerPl-mCnc

Result Turnaround Time

1-3 days

Specimen

Serum

Volume

3 mL

Minimum Volume

0.6 mL

Container

Red-top tube or gel-barrier tube

Patient Preparation

Collection of specimen at the onset of symptoms is needed to establish baseline values. A patient may have normal results at the onset of acute myocardial infarction, but some reach medical attention at or beyond the CK peak. It is recommended to support AMI diagnosis with three CK isoenzyme determinations: upon admission, 12 hours later, and 24 hours later.