Differential Diagnosis of Various Thrombocytopenias in Childhood by Analysis of Platelet Volume

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Abstract
Summary: Platelet volume was measured in 20 healthy children, 18 patients with acute idiopathic thrombocytopenic purpura (ITP), 24 patients with chronic ITP, 22 patients with aplastic anemia, and 17 patients with acute leukemia in childhood. The authors compared the platelet volume of these patients by use of peak platelet volume (PPV or mode of the platelet volume), mean platelet volume (MPV) and the percent of large platelets (PLP) as parameters of the platelet volume, and then studied the relationship between the platelet volume and the specific gravity of platelets from these patients. The following was the platelet volume of normal children: PPV was 6.7 ± 1.1 μm3, MPV was 9.9 ± 1.6 μm3 PLP was 26.0 ± 7.7%. All parameters of the platelet volume were remarkably large in chronic ITP, but only PPV was small in acute ITP. On the other hand, all parameters were small in both aplastic anemia and acute leukemia. In acute ITP and chronic ITP, the platelet volume returned to normal value after these thrombocytopenias disappeared. The platelet volume, however, still remained small even after remission in acute leukemia. There was better correlation between MPV and PLP than PPV and PLP. The density analysis of the platelets obtained from platelet-rich plasma (PRP) revealed that PLP in each medium (1.010 ∼ 1.052) of normal PRP increased slowly in proportion to the increase of specific density of the media. On the contrary, most of large platelets obtained from the patients with acute ITP and chronic ITP were especially contained in the medium of high specific density (1.052). Large platelets of aplastic anemia and acute leukemia, however, were found in both low and high density media. The authors believe that analysis of the platelet volume using above mentioned three parameters would provide good weapon in early differential diagnosis of acute ITP, chronic ITP, and aplastic anemia. And these findings also may suggest the difference of thrombopoiesis between acute ITP and chronic ITP. Speculation: It is often difficult to discriminate between acute ITP and chronic ITP, or chronic ITP and mild case of aplastic anemia at the first medical consultation. Analysis of the platelet volume of these patients is very useful in the differential diagnosis of these thrombocytopenic states; this fact may also suggest the difference of thrombokinetics and thrombopoiesis between acute ITP and chronic ITP. The analysis of the platelet volume may represent a good indicator of thrombopoiesis as well as reticulocytes in erythropoiesis.