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Creatine kinase reference intervals determined from a multi-centre data pool
R Bais1, R A Conyers, A M Rofe
1Division of Clinical Chemistry, Institute of Medical and Veterinary Science, Adelaide, South Australia.
Insights
New reference intervals for creatine kinase (CK) in Australia show higher values for males and females. The upper limit for males may require adjustment for myocardial infarction diagnosis.
Area of Science:
- Clinical Biochemistry
- Diagnostic Laboratory Medicine
- Enzyme Assays
Background:
- Establishing accurate reference intervals is crucial for interpreting laboratory test results.
- Creatine kinase (CK) is an enzyme commonly measured to assess muscle damage and aid in diagnosing conditions like myocardial infarction.
- Existing reference intervals may not accurately reflect current enzyme assay methodologies.
Purpose of the Study:
- To determine updated reference intervals for creatine kinase (CK) in an Australian population.
- To evaluate the suitability of these intervals for diagnosing myocardial infarction.
- To assess the distribution characteristics of CK levels in the studied population.
Main Methods:
- Data compilation from 10 Australian laboratories performing CK assays at 37°C.
- Utilizing N-acetyl cysteine-activated methods for CK measurement.
- Statistical analysis of pooled data to determine reference intervals, accounting for skewed distributions.
Main Results:
- Pooled creatine kinase distributions for both males and females were skewed and non-Gaussian.
- Established reference interval for females: 34–180 U/L.
- Established reference interval for males: 46–300 U/L.
Conclusions:
- The determined reference intervals provide updated values for CK in Australia.
- The upper limit of the male reference interval (300 U/L) may be too high for diagnosing myocardial infarction.
- Further investigation into population-specific upper limits for males, such as hospital inpatients, is recommended for diagnostic accuracy.
Abstract:
Reference intervals for creatine kinase assayed at 37 degrees C using N-acetyl cysteine-activated methods have been determined on data obtained from 10 laboratories throughout Australia. The pooled distributions for males and females are skewed towards higher values and cannot be transformed to Gaussian distributions. The reference interval for females was calculated to be 34 to 180 U/l and for males it was 46 to 300 U/l. However, if creatine kinase is to be used in the diagnosis of myocardial infarction, the upper limit of the reference interval for males is considered to be too high. It is concluded that for males, the upper limit may need to be determined on specific populations such as hospital inpatients.