Introduction: The aim of this study performed on Sysmex XN is to compare platelet values on citrate and MgSO4 (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 MgSO4 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 MgSO4 whereas 50% still showed clusters with citrate. Among those without platelet clusters on citrate, the mean relative difference between (citrate-MgSO4)/MgSO4 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 MgSO4 and -10.3% for Citrate. For the MgSO4 versus K2 EDTA regressions, the maximum absolute values of the 95% CI of the relative biases at 150 x 10(9)/L (5.45%) and 450 x 10(9)/L (3.56%) were below the desirable analytical objectives of the EFLM. Conclusion: In patients with K2EDTA-induced platelet clusters, MgSO4 is preferable to citrate. MgSO4 provides a bias with XN in fluorescence when compared to EDTA which is within analytical tolerance.

Background: In EDTA-induced pseudothrombopenia, citrate or MgSO₄ are recommended for platelet counting. Pre-analytical conditions are poorly defined for tubes containing MgSO₄ or citrate. In this study, we analyzed the impact of agitation of these tubes on platelet counts. Methods: K2EDTA, citrate, and MgSO₄ tubes from 70 patients were gently agitated on a wheel rotating at 20 rpm. Platelets were analyzed on the Sysmex XN analyzer at different times, and the percentage of platelet deviation from T0 was assessed and compared with the desirable bias of the EFLM. Results: at 180 min in fluorescence, the relative variation of platelets after shaking is 1.17% for K2EDTA, −29.76% for citrate, and −33.18% for MgSO₄, while for unshaken MgSO₄ platelets the variation is −1.3%. The reduction in platelet numbers when citrate or MgSO₄ tubes are shaken is linked to the appearance of platelet clusters. Conclusions: agitation of MgSO₄ and especially citrate tubes led to a decrease in platelet counts due to the formation of platelet aggregates; on the other hand, platelet counts on EDTA are virtually stable. During transport, we recommend putting sodium citrate and MgSO₄ tubes in an upright position and avoiding shaking them to avoid giving an erroneous platelet result.

Introduction: We investigated the stability and accuracy of platelets with MgSO ₄ and compared the results of blood counts between MgSO ₄ and K2EDTA. Methods: Platelet stability as a function of time was assessed on the XN Sysmex analyzer by comparing the percentage deviation to the desirable bias of the EFLM. Accuracy was determined by calculating the LoQ of platelets corresponding to a CV of 10%. Results from 250 patients were compared between K2EDTA and MgSO ₄ . Results: At 20°C, platelets were stable for 24 h in impedance, 10 h in fluorescence and at 4°C for 4 h in impedance, 2 h in fluorescence. This decrease is related to the formation of platelet aggregates. For platelets in fluorescence, LoQ is 4 × 10 ⁹ /L using MgSO ₄ . The results of the complete blood count did not differ between K2EDTA and MgSO ₄ except for the MCV, for which the median relative bias (MRB) with respect to K2EDTA was −5.6%. For MgSO ₄ platelets, the MRB is 2.9% in fluorescence and 11.9% in impedance. Conclusion: The use of MgSO ₄ with the XN produces results comparable to those obtained with K2EDTA, except for those related to MCV and for impedance platelets.