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Serum creatine kinase in the diagnosis of acute myocardial infarction. Optimal sampling frequency
Insights
For suspected acute myocardial infarction (MI), sampling creatine kinase (CK) and CK isoenzyme (CKMB) every 12 hours is a practical and cost-effective method. This frequency accurately captures peak CK levels in most patients, minimizing underestimation risks.
Area of Science:
- Biochemistry
- Cardiology
- Clinical Diagnostics
Background:
- Acute myocardial infarction (MI) diagnosis relies on serial cardiac enzyme measurements.
- Creatine kinase (CK) and its myocardial isoenzyme (CKMB) are key biomarkers.
- Determining optimal sampling frequency for CKMB is crucial for efficient patient management.
Purpose of the Study:
- To evaluate the optimal sampling frequency for creatine kinase (CK) and CK isoenzyme (CKMB) assays.
- To compare different sampling intervals (Q4hr, Q12hr, Q24hr) for detecting peak CK levels in suspected acute MI patients.
Main Methods:
- Retrospective review of CK/CKMB results from 314 patients with suspected acute MI.
- Comparison of peak CK values obtained via every four-hour (Q4hr) sampling versus simulated Q12hr and Q24hr sampling.
- Analysis of underestimation of peak CK levels (≥500 units/L) with less frequent sampling.
Main Results:
- Statistically significant differences in average peak CK were observed: Q4hr > Q12hr > Q24hr.
- Major underestimation of peak CK (≥500 units/L) occurred in only 3% of patients using the Q12hr method.
- The Q12hr sampling method demonstrated practical utility and cost-effectiveness.
Conclusions:
- Every 12-hour (Q12hr) sampling for CKMB is a practical and cost-effective strategy for patients with suspected acute MI.
- This sampling frequency minimizes the risk of significant underestimation of peak CK levels.
- Optimized sampling protocols can improve diagnostic efficiency and resource allocation in acute cardiac care.
Abstract:
To document optimal sampling frequency, we reviewed creatine kinase (CK) myocardial specific isoenzyme (CKMB) results in 314 patients with suspected acute myocardial infarction (MI). In 127 patients with elevated CK/CKMB, peak CK observed using all samples (every four-hour [Q4hr] method) was compared with results that would have been obtained had samples been taken on admission and either twice daily (every 12-hour [Q12hr] method) or once daily (every 24-hour [Q24hr] method). Although average peak CK was statistically different (Q4hr greater than Q12hr greater than Q24hr), major underestimation of peak CK (greater than or equal to 500 units/L) was uncommon (3%) using the Q12hr method, suggesting that Q12hr sampling is a practical, cost-effective approach for patients with suspected acute MI.