Relationship between platelet volume and anti-platelet autoantibodies in idiopathic thrombocytopenic purpura.

We used flow cytometry to explore the relationship between platelet volume and anti-platelet autoantibodies in 71 patients with idiopathic thrombocytopenic purpura (ITP). An increase in platelet volume was found more frequently in patients with a platelet count of less than 20,000/microliters. Platelet volume was larger in patients without anti-GPIIb/IIIa autoantibodies than in patients with these autoantibodies. Furthermore, the platelet count was significantly lower in patients without anti-GIIb/IIIa autoantibodies than in the patients with these autoantibodies. There was a positive correlation between a large platelet volume in patients with a platelet count of less than 30,000/microliters and high platelet-associated IgM levels. These results suggest that the platelet volume is related to the severity of thrombocytopenia in ITP.