Platelet formation in Mediterranean macrothrombocytosis.

: Platelet size distribution and survival parameters were studied in control subjects and ten subjects presenting Mediterranean macrothrombocytosis. The comparison showed that the latter group maintains a normal platelet circulating mass (thrombocytocrit) by combining normal platelet survival, increased splenic pooling and production of a reduced number of greatly enlarged cells. In addition to offering new insight into the megakaryocytic mechanisms that determine platelet size, the study of Mediterranean macrothrombocytosis indicates that platelet size distributions and survival parameters should be integrated in order to provide a meaningful picture of human platelet kinetics.