How is the CK relative index (CKI) calculated?

The calculation of the CK relative index (CKI) is focused on evaluating the proportion of creatine kinase myocardial band (CK-MB) to total creatine kinase (CK) in a sample. The purpose of determining CKI is to help in the diagnosis of myocardial infarction or other conditions involving cardiac muscle damage.

The correct formula to derive CKI is (CK-MB in μg/L / Total CK in IU/L) × 100. This formula expresses the concentration of CK-MB as a percentage of the total CK amount, thus giving insight into the specific contribution of CK-MB relative to the overall CK levels present in the blood sample.

This measurement is particularly valuable in a clinical context because an increased CKI suggests a higher likelihood of cardiac damage, more specifically relating to myocardial tissue. A higher CKI indicates that a greater proportion of the total CK is derived from myocardial sources, which can guide clinicians in diagnosing and managing conditions such as acute coronary syndrome.

Understanding the calculation and its clinical implications allows healthcare professionals to make informed decisions regarding patient care, and emphasizes the importance of using standard units (μg/L for CK-MB and IU/L for total CK) to maintain accuracy in the assessment.