Comparison of Platelet Count Results on the Sysmex XN Between Citrate or MgSO and K2 EDTA Anticoagulants

Introduction: The aim of this study performed on Sysmex XN is to compare platelet values on citrate and MgSO (TBX) in patients with K2EDTA-induced platelet clusters and to identify platelet biases of these matrices compared to K2EDTA.

Methods: Sixty patients with K2EDTA-induced platelet clusters were re-sampled with K2EDTA, citrate and TBX. Platelet results were then compared, and smears were analysed for clumping. Platelet results from 120 patients without K2EDTA-induced platelet clusters were compared between K2 EDTA, citrate, and MgSO with impedance and fluorescence modes. Biases from regressions were analysed.

Results: Out of the 60 patients with K2EDTA-induced platelet clusters, none showed platelet clusters with MgSO whereas 50% still showed clusters with citrate. Among those without platelet clusters on citrate, the mean relative difference between (citrate- MgSO )/MgSO was -12.7% in impedance and -9.8% in fluorescence. Among the 120 patients without K2EDTA-induced platelet clusters, in fluorescence the mean relative bias with respect to K2EDTA was -2.06% for MgSO and -10.3% for Citrate. For the MgSO versus K2 EDTA regressions, the maximum absolute values of the 95% CI of the relative biases at 150 × 10 /L (5.45%) and 450 × 10 /L (3.56%) were below the desirable analytical objectives of the EFLM.

Conclusion: In patients with K2EDTA-induced platelet clusters, MgSO is preferable to citrate. MgSO provides a bias with XN in fluorescence when compared to EDTA which is within analytical tolerance.