Protein C and Antithrombin III in polytransfused thalassemic patients

Seventy-four patients with β-thalassemia major were studied to test the hypothesis that a deficiency of protein C (PC) and antithrombin III (AT III), both antithrombotic proteins, could contribute to the pathogenesis of CNS thromboembolic lesions. In 70 patients, PC levels were found to be significantly lower than normal, whereas AT III activity was found to be lower only in 41 patients. The lowest values of PC and AT III were found in older splenectomized patients, a low PC value only was found in chronic hepatitis patients. Prothrombin time and fibrinogen were found to be particularly abnormal in patients with chronic hepatitis and without spleen. A relatively poor correlation was observed between PC and AT III (p < 0.02). PC correlated with age (p < 0.001), transfusional iron (p < 0.001) and ferritin (p < 0.001). It also correlated with serum albumin (p < 0.001), prothrombin time (p < 0.001) and fibrinogen (p < 0.02) and with serum transaminases (GPT) (p < 0.001). The same indexes correlated less significantly with AT III activity. Nevertheless, only 2 of our patients had CNS thromboembolic complications. It is probably that low clotting factors, hyperfibrinolysis and thrombocytopenia (which are common in chronic liver disease) could have the opposite effect on hemosasis from that of low levels of anticoagulant proteins such as PC and AT III