Comparison of Complete Blood Count Results Between K3-EDTA- and MgSO₄-Anticoagulated Samples Using a DxH800 Analyzer

Background/Objectives: In case of EDTA-induced pseudothrombocytopenia (PTCP), MgSO₄-anticoagulated tubes are recommended for platelet counting, requiring the collection of an additional tube. The aim of this study was to analyze whether complete blood count (CBC) and differential performed on MgSO₄-anticoagulated tubes were comparable to the results obtained on K₃-EDTA samples, and to characterize the stability of the CBC over a 24 h period. Methods: In 355 patients (70 with a confirmed PTCP and 285 without PTCP), we compared CBC results obtained on K₃-EDTA- and MgSO₄-anticoagulated tubes, using DxH800 analyzers. In 33 cases, a differential was available for both anticoagulants, and for 10 patients, samples were re-analyzed 6, 12, and 24 h after the first determination. Results: In the presence or absence of clumps, white blood cell (WBC) count, hematocrit, and mean corpuscular volume (MCV) were slightly lower in MgSO₄ than in K₃-EDTA tubes, whereas mean corpuscular hemoglobin concentration (MCHC) was slightly higher. Mean platelet volume (MPV) was significantly lower on MgSO₄- than on K₃-EDTA-anticoagulated tubes. Values were highly correlated between both anticoagulants, and mean relative biases (MRBs) were below Ricos's recommendations, except for MCHC and MPV. For differential, neutrophils were significantly lower on MgSO₄- in comparison to K₃-EDTA-anticoagulated tubes (MRB = -2.9%, below Ricos's optimal bias). The morphology of white blood cells (WBCs) was similar on both anticoagulants. During storage at room temperature, MCV and red cell distribution width increased slightly, but the increase was more pronounced in K₃-EDTA than in MgSO₄ tubes. Conclusions: CBC and differentials obtained with the DxH 800 analyzer on MgSO₄-anticoagulated samples are similar to those obtained with K₃-EDTA, except for MPV.