Lab Med Online.  2021 Jul;11(3):191-193. 10.47429/lmo.2021.11.3.191.

A Case of Spuriously Decreased White Blood Cell Count on an Automated Sysmex XN Hematology Analyzer: The Difference Between the WNR and WDF Channels

• Kim HJ
• Namgoong S
• Park CJ

• KMID: 2526068
• DOI: http://doi.org/10.47429/lmo.2021.11.3.191

Abstract

Most clinical laboratories utilize automated hematology analyzers for complete blood cell count (CBC). The CBC, including white blood cells (WBCs), is critical to determine patients’ clinical status; therefore, these results should be accurate and precise. We encountered a case that showed spurious WBC count from a Sysmex XN hematology analyzer (Sysmex Corporation, Japan). A 56-year-old man visited our center in October 2018 for follow-up of hepatocellular carcinoma with lung metastases. The initial WBC count measured by the Sysmex XN was 0.02×10³ /μL and the differential count was not available. A blood smear slide was automatically prepared and reviewed according to the laboratory protocol. The WBC count in the blood smear was within normal limits, much higher than that of CBC result, and there was no WBC aggregation. We also reviewed the raw data from the equipment, and we found the big difference between two channels (WBC and nucleated red blood cells [ WNR ] and white cell differential [ WDF ]) of the analyzer. The WBC count of the WNR channel was very low, but that of the WDF channel was 7.16×10³ /μL, consistent with that of the peripheral blood smear slide. The viscosity of the blood and the neutrophil respiratory burst activity were within normal limits. In conclusion, clinical laboratories operating hematology analyzers should be alert for this phenomenon. If the analyzer shows “Difference between channels”, it is important to check the raw results of the machine, prepare a blood smear and review by microscope, and report accurate results.

Keyword

Sysmex XN; Automated hematology analyzer; Spurious count; White blood cells; WNR channel; WDF channel

Figure

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  Fig. 1 (A) Peripheral blood smear (100×, Wright stain). (B) Scattergrams from the white cell differential (WDF) (left) and white blood cell and nucleated red blood cells (WNR) (right) channels of the Sysmex XN hematology analyzer.

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