Effect of hemolysis on canine kaolin-activated thromboelastography values and ADVIA 2120 platelet activation indices

Background The impact of hemolysis on thromboelastography (TEG) and platelet activation indices has not been evaluated. Objective The aim of this study was to investigate the influence of hemolysis induced mechanically (HM) and hemolysis induced by freezing (HF) on TEG, platelet counts (PLT), and platelet activation indicators. Methods Blood from 17 dogs was divided into the following samples: controls, HM, and HF. HM was induced by 20 repetitions of expulsion of blood through a 23 g needle. Freezing was at -80 degrees C, followed by warming to 37 degrees and dilution with equal parts room temperature blood at 22 degrees C. TEG variables that were examined included reaction time (R), coagulation time (K), angle (alpha), maximum amplitude (MA), and clot rigidity (G). Platelet indices were measured with the ADVIA 2120 hematology analyzer. Results Hematocrit (HCT) (mean +/- SD) for controls, HM, and HF were 0.41 +/- 0.02, 0.39 +/- 0.03, and 0.25 +/- 0.02 L/L, respectively, consistent with decreases in HCT of 4.8% (HM) and 39.0% (HF). HM resulted in decreased R (2.5 +/- 0.9 minutes compared with 5.2 +/- 1.9 minutes for controls; P < 0.001), and HF resulted in increased K (15.2 +/- 8.6 minutes compared with 5.3 +/- 4.0 minutes in controls; P < 0.01) and decreased alpha (20 +/- 11 degrees compared with 46 +/- 17 degrees in controls; P < 0.001). MA was decreased more in HF samples (26 +/- 2 mm) than in HM (38 +/- 8 mm) or control samples (49 +/- 9 mm; P < 0.0001). The same applied to G values. PLT decreased after HM but not after HF. Hemolysis of both types resulted in decreased mean platelet component (MPC) concentration: control, 19.3 +/- 2.0, HM 15.5 +/- 3.4, and HF 14.3 +/- 0.7 g/dL (P < 0.0001). Conclusion In hemolyzed samples decreased MPC and R suggested activated primary and secondary hemostasis, respectively, but decreased MA and G indicated reduced clot firmness, possibly due to hyporeactive platelets. TEG and platelet activation indices should be interpreted cautiously after hemolysis.