Protein C and antithrombin III in polytransfused thalassemic patients.

Seventy-four patients with beta-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 less than 0.02). PC correlated with age (p less than 0.001), transfusional iron (p less than 0.001) and ferritin (p less than 0.001). It also correlated with serum albumin (p less than 0.001), prothrombin time (p less than 0.001) and fibrinogen (p less than 0.02) and with serum transaminases (GPT) (p less than 0.001). The same indexes correlated less significantly with AT III activity. Nevertheless, only 2 of our patients had CNS thromboembolic complications. It is probable that low clotting factors, hyperfibrinolysis and thrombocytopenia (which are common in chronic liver disease) could have the opposite effect on hemostasis from that of low levels of anticoagulant proteins such as PC and AT III.