Change of routine coagulation parameters in plasma samples with different hematocrit values

Aim: There are many preanalytical variables affecting routine coagulation tests. Increased hematocrit (Htc) levels are one of these variables. However, no study has been conducted to determine the effect of low Htc values on coagulation tests. Therefore, in this study, we aimed to evaluate whether low Htc values affect coagulation tests besides high Htc values. Methods: Standard human plasma was injected into coagulation tubes containing 3.2% sodium citrate to reflect hematocrit rates of 5% to 75% and prothrombin time (PT), active partial thromboplastin time (aPTT), thrombin time (TT) and fibrinogen measurements were performed. Results: Three groups were formed according to Htc levels: A (5-25%), B (30-50%) and C (55-75%). PT (s) were found 13.7 +/- 0.30 in group A, 14.88 +/- 0.57 s in group B, 20.16 +/- 4.66 s in group C respectively. aPTT (s) results were 35.79 +/- 1.39 s in group A, 42.48 +/- 3.51 s in group B and 76.47 +/- 31.55 in group C. TT (s) results were found to be 26.42 +/- 0.77 s (group A), 28.24 +/- 1.17 s (group B) and 32.02 +/- 2.60 (group C). Fibrinogen levels (g/L) were measured as 2.30 +/- 0,05, 2.21 +/- 0,07 and 1.90 +/- 0.20 in groups A, B, C, respectively. For all measured parameters, group A reflecting low Htc was significantly (P < 0,0001) different from the other groups. Conclusion: Previous studies have reported that high Htc (> 55%) levels affected routine coagulation tests. In our study, low Htc (5-25%) values were also shown to cause errors in the test results.