Evaluation, including effects of storage and repeated freezing and thawing, of a method for measurement of urinary creatinine

• Published in: Scandinavian journal of clinical and laboratory investigation Vol. 63; no. 7-8; pp. 521 - 524
• Main Authors: Garde, A. H., Hansen, Å. M., Kristiansen, J.
• Format: Journal Article
• Language: English
• Published: Oslo Informa UK Ltd 01.01.2003; Taylor & Francis; Scandinavian University Press
• Subjects: Biological and medical sciences; Clinical Laboratory Techniques - standards; Cold Temperature; Creatinine; Creatinine - urine; Data Interpretation, Statistical; Freezing; freezing-thawing; Humans; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; method evaluation; Reference Standards; Regression Analysis; Reproducibility of Results; Sensitivity and Specificity; storage; Temperature; urine; Creatinine; Urine; Evaluation; Storage; Clinical biology; Conservation; Analytical method; Thawing; Measurement method; Freezing; Quantitative analysis
• ISSN: 0036-5513; 1502-7686
• DOI: 10.1080/00365510310000501

The aims of this study were to elucidate to what extent storage and repeated freezing and thawing influenced the concentration of creatinine in urine samples and to evaluate the method for determination of creatinine in urine. The creatinine method was based on the well-known Jaffe's reaction and measured on a COBAS Mira autoanalyser from Roche. The main findings were that samples for analysis of creatinine should be kept at a temperature of −20°C or lower and frozen and thawed only once. The limit of detection, determined as 3×SD of 20 determinations of a sample at a low concentration (6.1 mmol L), was 0.3 mmol L, and the recovery of a certified reference material was 97%. The relative precision at 3.15 mmol L was 2.3%. It was concluded that the method is appropriate for measurement of urinary creatinine.