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Estimation of Reference Change Value and Biological Variation of Creatinine Measurements in Healthy Individuals
Insights
This study assessed biological variation and reference change values (RCV) for creatinine using Jaffe and enzymatic methods in healthy adults. Results indicate individuality index (II) below 0.6, suggesting personalized RCV interpretation is more objective than population-based intervals.
Area of Science:
- Clinical Chemistry
- Biomarker Analysis
- Human Physiology
Background:
- Creatinine is a key biomarker for kidney function.
- Understanding biological variation is crucial for accurate clinical interpretation.
- Population-based reference intervals may not be optimal for all individuals.
Purpose of the Study:
- To evaluate the biological variation and reference change value (RCV) for serum creatinine.
- To compare creatinine analysis using Jaffe and enzymatic methods.
- To assess the suitability of population-based reference intervals versus individualized RCV.
Main Methods:
- Blood samples collected from 20 healthy adults (18-45 years) over four weeks.
- Creatinine analyzed using Jaffe and enzymatic methods on a Beckman Coulter AU2700 analyzer.
- Calculated analytical (CVA), intra-individual (CVI), and inter-individual (CVG) variations.
- Determined individuality index (II) and reference change value (RCV).
Main Results:
- Both methods showed low analytical variation (CVA < 3%).
- Individuality index (II) was consistently below 0.6 for both methods (0.32 Jaffe, 0.31 enzymatic).
- Calculated RCV values were 14.26% (Jaffe) and 13.43% (enzymatic).
Conclusions:
- The low individuality index suggests limited utility of population-based creatinine reference intervals.
- Individualized reference change values (RCV) offer a more objective approach for interpreting creatinine results.
- Accurate calculation of biological variation and increased clinical awareness are recommended.
Introduction:
The aim of the this study was to assess the biological variation and reference change value (RCV) for creatinine in healthy individuals aged 18 - 45 years using both Jaffe and enzymatic methods.
Methods:
Blood samples were collected from ten females and ten males, for four consecutive weeks in our labora-tory between November and December 2018. Samples were stored at -80°C before analysis and dissolved in one run and analyzed in duplicate in a single study with the Beckman Coulter AU2700 biochemistry analyzer. Data was evaluated using CV-ANOVA, and analytical (CVA), intra-individual (CVI), and inter-individual (CVG) variations were calculated. The RCV was calculated using the formula.
Results:
The average CVA calculated at 95% confidence interval for creatinine using Jaffe's method was 2.51%, CVI was 4.51%, and CVG was 14.17%. The same measures for creatinine were 2.43%, 4.21% and 13.69%, respectively, using the enzymatic method. The individuality index (II) was 0.32 for the Jaffe's method and 0.31 for the enzymatic method. The average RCV calculated bilaterally in the 95% confidence interval for the Jaffe's and enzymatic methods were 14.26 and 13.43, respectively.
Conclusions:
This manuscript has underlined the fact that the II of creatinine is less than 0.6 indicating that the use of population-based reference intervals is limited, and interpretation of the RCV and analysis might be a more objective approach. Taken together, these results suggest that it could be valuable to calculate biological variation correctly and increase clinical awareness.
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