Procoagulant Activity in Sickle Cell Anemia.

Sickle cell anemia (SCA) is associated with a hypercoagulable state that may contribute to the vaso-occlusive episodes observed in the disorder. Although numerous studies have been conducted to elucidate the mechanisms responsible for the prothrombotic state, the role of thrombogenisis in SCA complications remains controversial. We measured D-Dimer, thrombin-antithrombin complexes (TAT), prothrombin fragment 1+2 (F1+2), plasminogen activator inhibitor 1 (PAI-1), von Willebrand factor (vWF) and factor VIII (FVIII), in 42 homozygous sickle cell patients (HbSS), 26 women and 16 men, aged 14 to 48 years (mean age 26.8 years), 9 with hydroxyurea (HU) therapy, and correlated these data with clinical manifestations. Among the 42 studied patients, we found elevated plasma level (above the normal range) of these markers in 36 patients for D-Dimer (mean = 1481, range 280 – 5145 ng/mL), in 29 patients for TAT (mean = 7.35, range 2.2 – 45.0 microg/L) and FVIII (mean = 173, range 22.6 – 310.6%); in 25 patients for F1+2 (mean = 1.12, range 0.3 – 2.65 mM/L), in 21 patients for vWF (mean = 175, range 58 – 280%), and in 7 subjects for PAI-1 (mean = 41, range 11.5 – 103 ng/mL). There was no significantly correlation between hemostatic markers and the presence of leg ulcers or retinopathy in SCA patients. Factor VIII levels were significantly elevated in the 19 subjects with pulmonary hypertension, in the 5 with stroke and in the 33 patients who had not been treated with HU (p<0.05). TAT levels were also significantly elevated in the patients without HU (p<0.05). These findings confirmed the presence of a hypercoagulable state in patients with sickle-cell anemia, which could be driven by disease severity. (Supported by Fapesp 02/13801–7)