Abstract
A 71-year-old woman with EDTA-dependent pseudothrombocytopenia was presented. When she was admitted to authors' clinic, the platelet count was 1.9×104/cmm, obtained on an electronic counter using EDTA as anticoagulant. The light microscopy of the peripheral blood smears revealed the agglutination of plentiful platelets like “rocks”, but “platelet satellitism” phenomenon was not observed. No special change was demonstrated by electron microscopy. Plasma from this patient agglutinated homologous as well as autologous platelets in the presence of EDTA. However, agglutination did not occur in the blood with heparin, oxalate or citrate. This antiplatelet activity (APA) depending upon EDTA was active at 37°C as well as 20°C and inactivated after incubating at 56°C for 60 minutes. APA decreased in high concentration of EDTA, and its effect was inhibited by prostaglandln E1, dipyridamole but not by aspirin or adenosine.
These findings are interesting, relating to a mechanism of EDTA-dependent agglutination of platelets.
