Increased Level of Factor VIII and Physiological Inhibitors of Coagulation in Patients with Sickle Cell Disease.

Sickle cell disease (SCD) is a hemoglobinopathy characterized by hemolysis, oxidative stress, and vaso-occlusive crises. Thromboembolism also remains a serious complication and probably underestimated in the SCD. Our objective was to seek the existence of hemostasis abnormalities that predispose to thrombosis such as elevation of FVIII and Physiological inhibitors of coagulation deficiency. We studied 81 patients with SCD, including 32 homozygous S/S, 20 double heterozygous S/β thalassemia and 29 heterozygous S/A. Controls AA were in number 60. For each patient and control we assayed the physiological coagulation inhibitors (Protein C, Protein S and Antithrombin) and the clotting FVIII. We found a significant increase in FVIII in all phenotypes of SCD compared to controls. Also, a significant decrease in levels of protein C and S was observed in patients with sickle cell homozygous or double heterozygous S β Thalassemia compared to controls. As against, for antithrombin no difference was observed between patients and controls. These hemostasis abnormalities therefore reflect the existence of a pro thrombotic state in sickle cell disease that can explain the increase of incidence of thrombosis in this pathology. Factor VIII clotting consistently high in SCD may well be a prime therapeutic target in the treatment of thrombotic manifestations of this disease.