Functional compensation of the low platelet count by increased individual platelet size in a patient with May-Hegglin anomaly presenting with acute myocardial infarction.
Platelets are known to play a crucial role in normal hemostasis as well as in thrombus formation at sites exposed to blood flow, as in coronary thrombosis. Thus, low platelet count is a strong negative risk factor for the occurrence of arterial thrombosis, such as occurs in acute myocardial infarction. We encountered a patient with May-Hegglin anomaly, presenting with acute myocardial infarction in his sixth decade, even though his platelet counts had always been less than 50 x 10(3)/microl. We investigated the characteristics of his platelets under the effect of shearing and found that shear-induced platelet aggregation and binding of soluble von Willebrand factor (vWF) to platelets could be induced, even when the patient's platelet count was less than 10 x 10(3)/microl, but that virtually no aggregation or vWF binding by normal platelets could be induced by shearing when platelet counts were less than 50 x 10(3)/microl. We conclude that the low platelet counts in a patient with May-Hegglin anomaly can be functionally compensated for by larger individual platelets, in view of the vWF-dependent platelet thrombus formation occurring under the effect of blood flow and that that is why most patients with May-Hegglin anomaly do not have a bleeding tendency, even though their platelet counts are very low.
Department of Medicine, Tokai University, School of Medicine, Isehara, Japan. shinichi@is.icc.u-tokai.ac.jp
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Goto
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Kasahara
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Sakai
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Goto
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Ono
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Ikeda
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Jorquera
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Bravo
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Handa
D001792:Blood Platelets / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D006402:Hematologic Diseases / Q000097:blood / Q000150:complications*; D018056:Hemorheology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000209:etiology*; D010974:Platelet Aggregation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000032:analysis; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis; D013921:Thrombocytopenia / Q000097:blood* / Q000150:complications; D014841:von Willebrand Factor / Q000378:metabolism
D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D014841:von Willebrand Factor