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KMID : 0384119910110030537
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Korean Journal of Clinical Pathology
1991 Volume.11 No. 3 p.537 ~ p.544
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Development and Evaluation of Creatinine Reagent for ASTRA-8(r) and ASTRA-IDEAL(r)
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J. S. Lee
Y. K. Kim
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Abstract
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Creatinine, a nonprotein nitrogen( NPN) waste product of muscle metabolism, is filtered out of the bloodstream by glomerular filtration, and excreated in the urine with little or no reabsorption. The Jaffe method for creatinine analysis, first described in 1886, has the distinction of being the oldest clinical chemistry method still in common use. This assay is based on the reaction of creatinine with an alkaline solution of sodium picrate to form a red Janovski complex under 520nm absorbance. The most common methods for measuring creatinine employ the nonspecific alkaline picrate reaction, and thus noncreatinine chromogens in plasma increase the apparent plasma concentration. There are some types of analysis, spectrophotometric (520nm) end point, enzymatic hydrolysis, cation-exchange or reversed-phase chromatographic separation, isotope dilution GC/MS, and coupled enzymatic reactions. Because the reagents have been depended on imported materials in the clinical laboratories in Korea, the authors have developed a new reagent for creatinine analysis by automatic chemistry analyzer ( ASTRA-8R). In the evaluation of the newly developed reagent, the author performed the within-run precision study, day-to day variation study, patient comparison study, and compared the results with those obtained by Beckman original reagent. The results are summarized as follows : 1. The imprecision of new creatinine reagent is 1.17 - 4.38 % (CV) in the range of 1.3 - 5.9mg/dL and standard deviation is below O.O`img/dL. 2. Day to-day variance for 34 days is 3.29% for creatinine level at 1.3mg/dL. 3. The linearity IS very good in the range of medically significant range. 4. The accuracies by recovery study and patients comparison study are excellent and the correlation coefficient between the orginal and the new reagents method is 0.9991. 5. The newly developed reagent is not changed for about 3 months during evaluation period
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