CKMB: Optimal Testing Recommendations
Also known as: Creatine kinase, MB isoenzyme, CK-2 isoenzyme
- Routine measurement of CKMB is no longer indicated in the assessment of patients with a possible acute coronary syndrome (ACS) or in the assessment of patients with possible reinfarction.
- CKMB testing provides no incremental value to patient care, and its elimination in the U.S. can lead to millions of health care dollars saved without adversely affecting patient care.
- Troponin T or I are superior markers of myocardial injury for the diagnosis of acute myocardial infarction. Troponin T or I testing can be used to diagnose reinfarction, replacing CKMB as the marker of choice for the diagnosis of reinfarction. CKMB thus should be removed from routine order sets.
- If troponin T or I testing is not available, CKMB testing may be used in the assessment of patients with a possible acute coronary syndrome (ACS) or possible reinfarction.
- Note: CKMB can be interpreted in comparison to a simple reference interval. However, interpreting CKMB relative to the total CK [e.g., the CKMB index: CKMB/(total CK); a.k.a.: "relative percent"] may be superior to interpreting the total CKMB alone because skeletal muscle does contain CKMB and substantial degrees of skeletal muscle injury can elevate CKMB.
Guidelines for Test Utilization
What does the test tell me?
Prior to the development of troponin T and I testing, CKMB was the most specific marker of myocardial injury. [back to top]
When should I order this test?
CKMB testing is not routinely indicated for the diagnosis of acute myocardial infarction or reinfarction. Troponin T or I testing is the preferred marker for the diagnosis of acute myocardial infarction or reinfarction. [back to top]
When should I NOT order this test?
Do not order this test if troponin T or I testing is available. CKMB in addition to troponin offers no incremental diagnostic value. [back to top]
How should I interpret the result?
CKMB elevations can indicate myocardial injury. Injury can be caused by ischemia, infection (e.g., myocarditis), cardiac trauma (e.g., blunt force or surgical), cardiopulmonary bypass, coronary angiography, rejection of a transplanted heart, congestive heart failure, drug toxicity or pericarditis.
Is the test result diagnostic/confirmatory of the condition?
Elevations in CKMB are not absolute confirmatory for the diagnosis of acute myocardial infarction or reinfarction as there are other causes for elevations in CKMB, including ischemia, acute myocarditis, cardiac trauma (e.g., blunt force or surgical), cardiopulmonary bypass, coronary angiography, rejection of a transplanted heart, congestive heart failure or pericarditis. NOTE: While troponin T or I testing is superior to CKMB testing for the diagnosis of acute myocardial infarction, troponin T or I levels can be similarly elevated in many types of myocardial injury. [back to top]
Are there factors that can affect the lab result?
Skeletal muscle injury can elevate CKMB, leading to the false diagnosis of myocardial injury. If the CKMB index is used to diagnose myocardial injury, the CKMB index may not be elevated in cases of myocardial injury with concurrent substantial degrees of skeletal muscle injury. [back to top]
Are there considerations for special populations?
The test may be ordered for pediatric patients. However, the CKMB testing is rarely indicated as troponin T or I are superior markers of myocardial injury. [back to top]
What other test(s) might be indicated?
There is no routine indication for the measurement of CKMB. Troponin T or I testing is the preferred marker for the diagnosis of acute myocardial infarction or reinfarction. [back to top]
Thygesen K, Alpert JS, White HD; Joint ESC/ACCF/AHA/WHF Task Force for the Redefinition of Myocardial Infarction, et al. Universal definition of myocardial infarction. Circulation. 2007 Nov 27;116(22):2634-53.
Alvin MD, Jaffe AS, Ziegelstein RC, Trost JC. Eliminating creatine kinase-myocardial band testing in suspected acute coronary syndrome: a value-based quality improvement. JAMA Intern Med. 2017; 177:1508-12.
Hachey BJ, Kontos MC, et al; Trends in Use of Biomarker Protocols for the Evaluation of Possible Myochardial Infarction. JAHA. 2017;6:e005852. DOI: 10.1161/JAHA.117.005852.
Last reviewed: June 2020. The content for Optimal Testing: AACC's Guide to Lab Test Utilization has been developed and approved by the AACC Academy and AACC's Science and Practice Core Committee.
As the fields of laboratory medicine and diagnostic testing continue to grow at an incredible rate, the knowledge and expertise of clinical laboratory professionals is essential to ensure that patients received the highest quality and most useful laboratory tests. AACC's Academy and Science and Practice Core Committee have developed a test utilization resource focusing on commonly misused tests in hospitals and clinics. Improper test utilization can result in poor patient outcomes and waste in the healthcare system. This important resource geared toward medical professionals recommends better tests and diagnostic practices. Always consult your laboratory director to make sure these recommendations are appropriate for your patient population.