Thrombotic thrombocytopenic purpura. A case investigated with 111In-oxine-labelled platelets.

A 34-year old woman presented with the clinical and laboratory features of thrombotic thrombocytopenic purpura (TTP). Studies with isologous platelets labelled with 111In-oxine revealed a short half-life of circulating platelets (18,5 hours) and destruction of the transfused platelets in the spleen, liver and bone marrow. There was no scientigraphic evidence of deposition of labelled platelets in the vasculature. The patient was treated with daily fresh frozen plasma transfusions, but no improvement in platelet count or serum urea level was noted. Although there was no clinical evidence of a bleeding tendency at the time, the patient had a fatal cerebrovascular haemorrhage. The findings in this case suggest that an immune type destruction of platelets may occur in TTP.