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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 micrometer 3, MPV was 9.9 +/- 1.6 micrometer 3, 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 approximately 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 diagnosos of acute ITP, chronic ITP, and aplastic anemia. And these findings also may suggest the difference of thrombopoiesis between acute ITP and chronic ITP.

The pathogenesis of the anemia of chronic renal failure is multifactorial. Anabolic steroid has been reported to be of therapeutic value, but it is difficult to use because of its side effect especially in children. We used an analog of activated vitamin D (1α-OH-D3) in 6 haemodialysis patients with anemia. After lα-OH-D3 treatment, hemoglobin and hematocrit values didn't change in these patients, but frequency of blood transfusion has been decreased. We examined serum erythropoietin by in vitro bioassay and haemoaggulutination inhibition assay. And we also examined the effect of various vitamin D metabolites on in vitro growth of granulopoietic and erythropoietic colonies. lα-OH-D3 is suspected to have anabolic steroid like effect.