92 - Stability of common analytes and urine particles stored at room temperature before automated analysis
Autor(s): F. Manoni, S. Valverde, A. Caleffi, M.G. Alessio, M.G. Silvestri, R. De Rosa, A. Zugno, M. Ercolin, G. Gessoni
Issue: RIMeL - IJLaM, Vol. 4, N. 3, 2008 (MAF Servizi srl ed.)
Page(s): 192-198
Background. Central outpatient laboratories may need to process large numbers of urinary samples that arrive 4-6 hours after collection. Furthermore, in certain settings, clinics may have difficulty assuring that the urine arrives at the laboratory in refrigerated containers. The aim of this study is to assess the stability of urine samples stored at room temperature for delayed automated dipstick analysis and automated particle examination. Methods. We considered 300 samples collected from adult outpatients. Urinalysis was done at intervals of 0, 2, 4 and 6 hours (+15 minutes) after collection. For chemical examination 200 samples were tested using an automated analyser and strips supplied by Menarini and 100 samples were tested using an automated analyser and strips supplied by Siemens. For particle analysis 250 samples were tested using a Sysmex UF 100 analyser and 50 using an Iris iQ 200 analyser. Results. Among the analytes on test strips the authors observed a statistically significant diminution in samples positive for proteinuria. For particle analysis we observed a significant decrease in the number of casts, RBC ad WBC were quite stable. A significant increase of samples with high bacteriuria was observed in samples stored at room temperature for up to six hours. Conclusions. Data obtained in this study suggest that urine samples could be stored at room temperature for up to 2 hours without significant variation in the results of the physical-chemical and particle analysis. With a longer storage period we observed a decay in quality of the samples: bacterial overgrowth, lysis in RBC, WBC and casts.