Routine sample transportation of centrifuged barrier tubes impacts certain chemistry analytes

The preanalytical phase of testing, including sample transportation, is a common source of error in laboratory testing. Previous studies have shown inversion of centrifuged plasma separator tubes (PST) results in elevation in certain analytes. However, it remains unclear if routine transportation practices, without full inversion, can have a similar impact. This study used 12 residual samples submitted in PST and 4 PST tube samples collected from healthy donors. All samples were measured at baseline. Analytes measured were white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) using the Sysmex XN-1000 and potassium (K), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), sodium (NA), and alanine aminotransferase (ALT) using the Ortho Vitros 4600. The samples were split into two groups: 1 group was placed vertically in racks and the other group were laid horizontally in a messenger bag-style soft-sided cooler used by lab couriers. A cold pack was placed in the bag, equidistant from both groups of samples. To mimic courier transportation, the bag was carried for 30 min, returned to the laboratory and immediately analyzed. Subsequently, the samples were re-centrifuged and analyzed again. Statistics were performed using GraphPad Prism. LDH increased following transportation for vertical and horizontal samples and remained elevated despite re-centrifugation. K was only increased in the horizontal samples following re-centrifugation. Notably, AST as well as WBCs, RBCs, and PLTs all increased following transportation, but dropped to baseline concentrations following re-centrifugation. Centrifuged PSTs should be kept in a vertical position during transportation by courier. Re-centrifugation of plasma gel tubes after transportation may be necessary for certain chemistry tests.