Spurious thrombocytopenia due to EDTA-independent cold-reactive agglutinins.

Spurious thrombocytopenia is an infrequent laboratory problem that may be confused with true thrombocytopenia, leading to inappropriate testing to determine the cause of the thrombocytopenia. Spurious thrombocytopenia has been associated most often with temperature-independent, ethylene diaminetetraacetic acid (EDTA)-dependent antibodies. Two cases of spurious thrombocytopenia due to temperature-dependent, EDTA-independent agglutinins are reported. Modification of sample processing to maintain the sample near 37 degrees C was necessary to obtain accurate platelet counts. The initial blood cell histograms were abnormal in each case, leading to the diagnosis. However, in one case significant platelet agglutination was not flagged on a subsequent histogram. These cases illustrate that spurious thrombocytopenia may be caused by more than one type of agglutinin and that not all samples with in vitro agglutination are detected by blood cell histograms.