Indian Journal of Health Sciences and Biomedical Research KLEU (Jan 2017)
Effect of storage and temperature on two biochemical analytes (creatinine and urea) in pooled serum samples stored at -20°C
Abstract
Introduction: Creatinine and urea are nonprotein nitrogenous compounds which are eliminated from the body. Creatinine is a word obtained from a Greek term "Kreas" meaning flesh. An anhydrous form of creatine is creatinine. Around 0.5% of total muscle weight constitutes creatine. Muscle, brain, blood, etc., are the tissues, in which creatinine is present as high-energy compound, phosphocreatine, and creatine as free compound. Optimal storage of serum specimens in biobanks for long time for multicenter reference interval studies remains to be determined. Hence, in this context, the present study was undertaken to determine the effect of storage time and temperature on the laboratory results of urea and creatinine in pooled serum samples. Objective: To determine the effect of storage and temperature on two biochemical analytes (creatinine and urea) in pooled serum samples stored at -20°C. Materials and Methods: The study comprised ten pooled serum samples. Each pooled serum sample was prepared by mixing ten individual serum samples. The serum samples were used for the estimation of effect of storage and temperature on two biochemical analytes (creatinine and urea) in pooled serum samples stored at -20°C in semi-automated analyzer by kit method. Results: The results of the present study on creatinine concentration were found to increase above the normal levels in ten pooled serum samples after storage for 10 days at -20°C. Concentration of urea was found to increase above the normal levels (>20-40 mg/dL) in two samples out of ten, whereas other eight samples were found to be within the normal range. Conclusion: The levels of creatinine were affected due to storage at -20°C for 10 days. However, urea retained its stability when stored at -20°C for 10 days. Thus, to ensure valid results, the samples should be analyzed within 24 h of collection.
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