Effect of tube filling order on specific coagulation parameters in healthy subjects

Abstract Background: In this study, the authors attempted to determine if there was any effect of tube filling order on both routine (prothrombin time [PT], activated partial thromboplastin time [APTT], and fibrinogen) and specific coagulation parameters (protein S, protein C, antithrombin III, factor V Leiden, plasminogen, and D-dimer). Methods: Fifty-seven consecutive patients having coagulation parameters within the reference range (mean age ±SD, 32.14±5.59 years) were included in the study. In drawing blood, the first 2 tubes were 3.2% citrated coagulation tubes. Routine and specific coagulation parameters were studied on both tubes, and the results were compared using a paired sample t-test. Results: The comparison of all parameters revealed statistically-insignificant results. The difference in the levels of protein C between the 2 tubes approached significance (P=0.053). Conclusion: This study has shown some evidence that tube filling order in healthy subjects does not play a significant role on routine and specific coagulation parameters.