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Application of the Fluorescence Method on Sysmex XN9000 Hematology Analyzer for Correcting Platelet Count in
Jiankai Deng1, Shuhua Xie1, Yaoming Chen1
1Department of Laboratory Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
Objective:
Although small red blood cells are a well-known analytical pitfall that could cause artifactual increase of the platelet count, limited information is available on the accuracy of impedance platelet counting in cases with microcytosis. The aim of this study is to assess the accuracy of impedance platelet counting in the presence of small red blood cells, and to establish the optimal mean corpuscular volume (MCV) cutoff to endorse fluorescence platelet counting.
Methods:
In this study, platelet counts estimated by the impedance method on the Sysmex XN9000 analyzer (Sysmex, Kobe, Japan) were compared with those provided by the fluorescence method. The accuracy of impedance platelet counting was assessed. Receiver operating characteristic curve was used to evaluate the performance of MCV in predicting falsely increased platelet counts.
Results:
There was a tendency for the impedance method to overestimate the platelet count in samples with 70 fL < MCV ≤ 80 fL, 60 fL < MCV ≤ 70 fL, MCV ≤ 60 fL. Receiver operating characteristic curve analysis showed that a 73.5fL cutoff of MCV was highly sensitive in predicting falsely increased platelet counts.
Conclusion:
In cases with MCV < 73.5 fL, we strongly suggest that the platelet counts obtained by the impedance method on the Sysmex XN9000 analyzer should be checked and corrected by fluorescence counting.
Insights
Small red blood cells can falsely elevate platelet counts. A mean corpuscular volume (MCV) below 73.5 fL indicates a need to confirm impedance platelet counts using fluorescence methods.
Area of Science:
- Hematology
- Clinical Pathology
Background:
- Small red blood cells (microcytosis) are a known interference in automated platelet counting.
- The accuracy of impedance-based platelet counting in microcytic samples requires further investigation.
Purpose of the Study:
- To evaluate the accuracy of impedance platelet counting with small red blood cells.
- To determine an optimal mean corpuscular volume (MCV) cutoff for differentiating accurate from inaccurate impedance platelet counts.
Main Methods:
- Comparison of platelet counts from impedance (Sysmex XN9000) and fluorescence methods.
- Receiver operating characteristic (ROC) curve analysis to assess MCV's predictive performance for false platelet counts.
Main Results:
- Impedance method showed a tendency to overestimate platelet counts when MCV was ≤ 80 fL.
- An MCV cutoff of 73.5 fL demonstrated high sensitivity in identifying falsely elevated platelet counts.
Conclusions:
- For samples with MCV < 73.5 fL, fluorescence platelet counting is recommended to verify results obtained by impedance methods on the Sysmex XN9000.
- This approach helps mitigate inaccuracies caused by microcytosis in platelet enumeration.
