Macrothrombocytes and thrombocytopenia: A variant in healthy greek and italian subjects

Abstract

The authors had previously established the distribution of platelet counts and platelet volume parameters in Anglo-Saxon Australians in health and through the course of various diseases during which the platelet counts and/or platelet turnover deviated markedly from the range obtained in healthy subjects. Mean platelet size remained in the range for the healthy group in all the clinical states studied. Platelets of any individual ranged from 1 μ 3 to over 30 μ 3 in size and the average platelet volumes of the different subjects from 9.3 to 15.6 μ 3 (EDTA 22°). Greek and Italian patients frequently had anomalous platelet counts and platelet size parameters. A group of 100 healthy Mediterranean subjects was therefore studied. The platelet counts were found to be much lower and platelet sizes much larger than those established for the Anglo-Saxon group. Only one-third of subjects in the variant group fell into the 90% Anglo-Saxon range by both count and size. In this healthy variant group, the parameter of mean platelet size and the platelet count of the various subjects showed an inverse relationship such that SIZE × COUNT was roughly constant (r = 0.8). The same product for the Anglo-Saxon group yielded a 5% to 95% range from 4,600 to 10,000 and all the Mediterranean subjects so far studied also fell into this range; patients with a significant thrombocytopenia or thrombocytosis did not. A review of 10 Greek or Italian subjects diagnosed as having idiopathic thrombocytopenic purpura and subjected to splenectomy and/or steroid treatment revealed that platelet survival studies developed for the Anglo-Saxon population were technically invalid in the variant group. In the absence of significant clinical manifestations and bleeding, clotting and platelet function abnormalities, these cases must be reclassified as healthy despite platelet counts below 50,000 per mm. 3 whole blood. It was concluded that this is a previously unrecognized platelet variant in apparently normal Mediterranean subjects.