Post-analytical stability of 23 common chemistry and immunochemistry analytes in incurred samples

Storage of blood samples after centrifugation, decapping and initial sampling allows ordering of additional blood tests. The pre-analytic stability of biochemistry and immunochemistry analytes has been studied in detail, but little is known about the post-analytical stability in incurred samples.

We examined the stability of 23 routine analytes on the Dimension Vista® (Siemens Healthineers, Denmark): 42-60 routine samples in lithium-heparin gel tubes (Vacutainer, BD, USA) were centrifuged at 3000×g for 10min. Immediately after centrifugation, initial concentration of analytes were measured in duplicate (t=0). The tubes were stored decapped at room temperature and re-analyzed after 2, 4, 6, 8 and 10h in singletons. The concentration from reanalysis were normalized to initial concentration (t=0). Internal acceptance criteria for bias and total error were used to determine stability of each analyte. Additionally, evaporation from the decapped blood collection tubes and the residual platelet count in the plasma after centrifugation were quantified.

We report a post-analytical stability of most routine analytes of ≥8h and do therefore - with few exceptions - suggest a standard 8hour-time limit for reordering and reanalysis of analytes in incurred samples.