Background: Sickle cell disease (SCD) is considered to be a hypercoagulable state that contributes to the morbidity associated with the disease. Numerous mechanisms can attribute to this hemostatic activation among these patients. Objectives: The study was designed to evaluate changes in hemostatic tests, coagulation inhibitors, fibrinolysis, and phosphatidylserine exposure on red blood cells (RBCs) among patients with SCD during both a vaso-occlusive crisis (VOC) and a steady state. Materials and Methods: This observational study comprised 61 patients with SCD, 2 to 16 years old, and 65 healthy patients. Thrombophilia evaluation included prothrombin time (PT), activated partial thromboplastin time (aPTT), protein C and S, d-dimer and Annexin V expression. The independent t test and one-way analysis of variance test were used for comparison of the mean of different samples. Results: During steady state, patients with SCD had longer PT (14.36 ± 0.98 and 13.32 ± 0.79 s), longer aPTT (31.48 ± 2.52 and 30.11 ± 2.04 s), lower protein C (90.95 ± 20.11 and 98.18 ± 18.42 U/L), lower protein S (60.18 ± 12.96 and 80.8 ± 12.67 U/L), and higher d-dimer (1.19 ± 1.25 and 0.27 ± 0.23 μg/mL) levels than the control group, respectively, P < 0.05. Furthermore, a longer PT (15.02 ± 2.11 s), lower protein C (69.21 ± 16.32 U/L), lower protein S (46.56 ± 9.47 U/L), and higher d-dimer levels (3.44 ± 2.62 μg/mL) were reported during VOC compared to steady state. The mean percentage of RBCs expressing Annexin V was assessed in only 10 patients with SCD and eight in the control group. The mean percentage during a VOC (7.66 ± 3.63) was higher than that during steady state (1.57 ± 0.94) and in the control group (0.41 ± 0.15), P = 0.000. Pearson correlation revealed that d-dimer is significantly associated with hemoglobin, indirect bilirubin, and lactate dehydrogenase, P < 0.05. Conclusion: Patients with SCD, particularly during VOC, undergo significant hematologic alterations that increase their risk of developing coagulation activation-related complications.
