Pseudothrombocytopenia induced by incubation at 37 ℃ in ethylenediaminetetraacetic acid tubes

Ethylenediaminetetraacetic acid (EDTA) is the anticoagulant currently used for cell blood counts. Several studies showed that exposure of platelets (PLTs) to EDTA for a short period of time promote tyrosine phosphorylation of certain proteins, events that are related to activation. Spuriously low PLT counts were observed in a patient with cold agglutinins after the blood being warmed at 37 ℃ in EDTA tubes. Some cloudy polymers were found on peripheral blood smear after incubation at 37 ℃ for 15 minutes. These data suggest that PLT were activated after being warmed to 37 ℃ with EDTA. This process initiated coagulation and generated fibrin and PLT polymers from PLT agglutination and release. This case report hence describes a very rare phenomenon, which produces a spuriously low PLT counts caused by warming of EDTA tubes at 37 ℃.