[Influence of temperature and delayed centrifugation: stability studies of 28 analytes currently analysed]

A large amount of off-site blood sampling are analysed in our laboratory with a variable conveying time of up to 7 hours. Fifteen healthy volunteers were included in this study. The aim was to evaluate the stability of current analytes in regard to the temperature and the time before centrifugation. Whole blood obtained by venipuncture was collected into collector tubes respectively with heparinate for plasma recovery and on dry tube for TSH determination. All the analytes, except potassium and phosphate showed a good stability at +22 degrees C, with a centrifugation delay of up to 7 hours. A sample storage at +4 degrees C didn't show any better stability for potassium but allowed a significant improvement of phosphate stability. Sample conservation at +22 degrees C can be considered as well suited for current biochemistry determinations. However, in specific calcium and phosphate metabolism investigations, samples preservation at +4 degrees C can be justified. Finally, in potassium assay, regardless of the chosen conservation temperature, centrifugation should occur within 2 hours of sampling.