SCREENING FOR EDTA-DEPENDENT DEVIATIONS IN PLATELET COUNTS AND ABNORMALITIES IN PLATELET DISTRIBUTION HISTOGRAMS IN PSEUDOTHROMBOCYTOPENIA

Screening for pseudothrombocytopenia caused by in vitro platelet clump ing has been performed in 45 000 subjects attending a general hospital . In our region, the observed prevalence of EDTA-induced pseudothrombo cytopenia in blood samples with an initial platelet count below 150x10 (9)/l was estimated to amount to 0.1%. EDTA-induced pseudothrombocytop enia was confirmed by detection of platelet aggregates by means of mic roscopic evaluation from the blood smear: In routine investigations, p seudothrombocytopenia could be highly suspected when the Sysmex NE 800 0 showed characteristic peculiarities in the white blood cell (WBC) sc attergram and histogram. Platelet aggregation is avoided in such cases by the use of citrate as an anticoagulant instead of EDTA. Pseudothro mbocytopenia was detected in 46 subjects. As a screening test for pseu dothrombocytopenia, increased cut-off values derived from the WBC hist ogram demonstrated 90% sensitivity and 100% specificity. Automated fla gging for platelet clumps, deviations reflecting MPV, or PDW abnormali ties revealed lower scores with respect to sensitivity.