Validation of the body fluid module on the new Sysmex XN-1000 for counting blood cells in cerebrospinal fluid and other body fluids

Background: We evaluated the body fluid (BF) module on the new Sysmex XN-1000 for counting blood cells. Methods: One hundred and eighty-seven BF samples [73 cerebrospinal fluid (CSF), 48 continuous ambulatory peritoneal dialysis (CAPD), 46 ascites, and 20 pleural fluid] were used for method comparison between the XN-1000 and manual microscopy (Fuchs-Rosenthal chamber and stained cytospin slides) for counting red blood cells (RBCs) and white blood cells (WBCs) (differential). Results: Good agreement was found for counting WBCs (y=1.06x+0.09, n=67, R-2=0.96) and mononuclear cells (MNs) (y=1.04x-0.01, n=40, R-2=0.93) in CSF. However, the XN-1000 systematically counted more polymorphonuclear cells (PMNs) (y=1.48x+0.18, n=40, R-2=0.99) compared to manual microscopy. Excellent correlation for RBCs >1x109/L (y=0.99x+116.56, n=26, R-2=0.99) in CSF was found. For other fluids (CAPD, ascites and pleural fluid) excellent agreement was found for counting WBCs (y=1.06x+0.26, n=109, R-2=0.98), MNs (y=1.06x-0.41, n=93, R-2=0.96), PMNs (y=1.06x+0.81, n=93, R-2=0.98) and RBCs (y=1.04x+110.04, n=43, R-2=0.98). By using BF XN-check, the lower limit of quantitation (LLoQ) for WBC was defined at 5x10(6)/L. Linearity was excellent for both the WBCs (R-2=0.99) and RBCs (R-2=0.99) and carry-over never exceeded 0.05%. Conclusions: The BF module on the XN-1000 is a suitable tool for fast and accurate quantification of WBC (differential) and RBC counts in CSF and other BFs in a diagnostic setting.