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Philip L. Cimo, MD
JAMA. 1974;229(7):766-767. doi:10.1001/jama.1974.03230450016011.
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To the Editor.—  In their recent article (227:628, 1974), Kjeldsberg and Hershgold pointed out several conditions that may result in artifactual thrombocytopenia when platelet counts are made by automated methods.We recently saw a patient with still another type of pseudothrombocytopenia. She is 83 years old and was referred from another hospital because of rectal bleeding and "thrombocytopenia," with a platelet level of "10,000"/cu mm. There were no petechiae or ecchymoses, and the bleeding was localized to an anal fissure. The automated platelet count was 60,000/cu mm. However, the peripheral smear showed large masses of platelets that were clumped (Figure), and platelet clumping in an edetic acid-treated specimen made counting by phase microscopy unreliable. Platelet clumping also occurred in oxalated, citrated, and heparinized blood and was present to a slightly less degree in nonanticoagulated capillary blood obtained by fingerstick.The patient's serum did not contain platelet antibodies by the51


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