Intracranial hemorrhage and circulating coagulation inhibitor in beta-thalassemia major.

A syndrome of intracranial hemorrhage with gross prolongation of the prothrombin and partial thromboplastin times, with normal thrombin time, fibrinogen concentrations, and coagulation factor assays is described in four children with homozygous beta-thalassemia. Mixing experiments and plasma thromboplastin inhibition tests revealed a persistent abnormality which was consistent with the presence of a circulatory prothrombinase inhibitor. The origin of this previously unreported inhibitor in thalassemia remains speculative.