Evaluation of the new body fluid mode on the Sysmex XE-5000 for counting leukocytes and erythrocytes in cerebrospinal fluid and other body fluids

Background: We evaluated the body fluid (BF) mode on the new Sysmex XE-5000 analyzer. Methods: Red (RBC) and white blood cell (WBC) (differential) counts of BFs (139 patient samples and 87 normal samples) were measured and compared to the Fuchs-Rosenthal chamber and stained cytospin slides. Results: Extended cell counting using the BF mode was noted to have an improved WBC detection limit (CV20%) of 10x10(6)/L. Excellent agreement with the manual method was observed for most BFs [mean bias +2 to 6x10(6)/L for cerebrospinal fluid (CSF) and -1 to 12x10(6)/L for other fluids]. In CSF, the BF-mode counted more WBC (polymorphic nuclear cells) compared with the manual method (mean bias +5 to 6x10(6)/L), especially in samples with low cell counts (<20x10(6)/L). Carry over was negligible (mostly <0.17%) and linearity was excellent (mean bias <5%). The reference ranges for CSF (n=87) were RBC 0x10(6)/L, WBC and mononuclear <7x10(6)/L, and polymorph nucleated cells <3x10(6)/L. Conclusions: The BF mode on the Sysmex XE-5000 offers rapid and accurate RBC and WBC (differential) counts in clinically relevant concentration ranges in CSF and other fluids. In addition, the exclusion of high fluorescent cells, such as mesothelial cells and macrophages from WBC counting may reduce the number of manual analyses in pleural fluids and ascites. Clin Chem Lab Med 2010;48:665-75.