Erroneous monocyte and neutrophil counts with the Sysmex NE-1500 in patients recovering from bone marrow aplasia

The Sysmex NE-1500 is a haematological analyser which offers five-part differential counts. The instrument was submitted to an extensive evaluation procedure before acceptance to the laboratory and was found to perform satisfactorily. However, problems arose in clinical practice with the analysis of samples from patients recovering from bone marrow aplasia. Falsely low monocyte counts and, controversely, falsely high neutrophil counts were found in these patients. Only a minority (13%) of these samples were flagged as abnormal by the instrument. The most alarming consequence of these results is the overestimation of neutrophils and the exclusion of these patients from reimbursement for treatment with growth factors. We conclude that in patients recovering from aplasia, differential counts performed with the Sysmex NE series should always be checked manually.