Hematology Case Study - WBC Abn Scattergram w-NRBC

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This is an example (see PDF) of false leukocytosis due to the presence of NRBCs. The NRBC result is unreportable due to a large population of NRBCs captured in the WNR channel which are above the reportable range of the analyzer. The WBC count is normally measured in the WNR channel on XN-series analyzers. However, in the presence of interference in the WNR channel, the analyzercan obtain the WBC count from the WDF channel. The “&D” next to the WBC result indicates it was obtained from the WDF channel.

There was not clear separation between cell populations in both the WNR and WDF channels due the presence of immature NRBC forms. The larger nuclei found in pronormoblasts (rubriblasts) and basophilic normoblasts (prorubricytes) is similar in size to the nucleus of the non-basophil WBCs in the WNR scattergram. Because of the similarity in size, the WBC and NRBC populations overlapped. This generated the “WBC Abn Scattergram” flag. In such cases it is recommended that the NRBC count from a manual differential be used to calculate the corrected WBC count using the total nucleated cell count and the formula below:

WBC = [TNC X 100] / [(NRBCs per 100) + 100]

The TNC (‘uncorrected’ WBC count) can be found in the Service/WNR tab of the Browser Screen.

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