François Magne - Academia.edu (original) (raw)

Papers by François Magne

Objectives: In thrombocytopenia, high accuracy and precision of low platelet count is essential f... more Objectives: In thrombocytopenia, high accuracy and precision of low platelet count is essential for appropriate decisions. The recently introduced Sysmex XN2000 analyzer (Sysmex, Kobe, Japan) offers 3 methods for platelet counting: impedance (PLT-I), optical (PLT-O), and a new fluorescence method (PLT-F). The precision of the PLT-F method in blood samples with platelet counts less than 50 ×10 3 /µL (50 × 10 9 /L) was investigated and compared with the ICSH CD61-ImmunoPLT reference method. For comparison, PLT-I and PLT-O were determined on the Sysmex XN2000 and Sysmex XE2100 analyzer. Methods: Blood samples with platelet counts less than 50 ×10 3 /µL (50 × 10 9 /L) (n = 37) were analyzed on the Sysmex XN2000 and XE2100 analyzers. The CD61-ImmunoPLT method was performed on a Beckman Coulter FC-500 flow cytometer (Miami, FL). Results: At a platelet count of 20 ×10 3 /µL (20 × 10 9 /L), reproducibility for PLT-I, PLT-O, and PLT-F on the XN2000 demonstrated coefficients of variation of 9.3%, 8.5%, and 3.0%, respectively. Correlation between PLT-O on the XN2000 and XE2100 yielded an r value of more than 0.977. Linear regression analysis between the PLT-F and CD61-ImmunoPLT methods resulted in a PLT-F of 0.71*CD61 – 0.8 (r = 0.988). Linear regression between PLT-F and PLT-O on the XN2000 resulted in a PLT-F of 1.05*PLT-O – 2 (r = 0.975), and using the transfusion threshold of 20 × 10 9 /L platelets resulted in a PLT-F of 0.90*PLT-O – 0.4 (r = 0.956). Conclusions: The new PLT-F method demonstrated excellent results for reproducibility in samples with platelet counts less than 50 × 10 9 /L. PLT-F could be helpful in making better decisions for platelet transfusions. In subjects with thrombocytopenia, high accuracy and high precision of low platelet count is essential for appropriate clinical decisions. A platelet transfusion threshold of 10 × 10 3 / µL (10 × 10 9 /L) is recommended for prophylactic transfusion in stable patients, whereas a level of less than 20 × 10 3 /µL (20 × 10 9 /L) is recommended in case of risk factors such as sple-nomegaly, coagulation factor deficiencies, and rapid decrease in platelet count or severe bleeding. During follow-up, platelet counts between 50 and 100 ×10 3 /µL (50-100 × 10 9 /L) are used as an indication of the potential need for platelet transfusion. 1-3 These delicate differences require an accurate method for determining the platelet count. For this purpose, the routinely used Sysmex XE2100 analyzer (Sysmex, Kobe, Japan) is equipped with 2 platelet detection methods, the impedance method (PLT-I) and the optical method (PLT-O). In the majority of samples, platelets are accurately counted using PLT-I. The PLT-O count is more accurate for platelet counts below 100 × 10 3 /µL (100 × 10 9 /L). 4,5 However, for samples from patients undergoing chemotherapy, the impedance count will yield more accurate results. 6 Deviations are probably caused by the staining of white cell fragments after apoptosis. 7 The Sysmex XN2000 automated hematology analyzer (Sysmex) is a recently launched multiparameter cell counter with innovative methods and an additional possibility for body fluid analysis. New functions have been added to enhance precision in blood cell counting by applying new fluorescent dyes, a nucleated RBC correction function for WBC counting in all specimens (WNR-channel), and a newly added measurement mode for specimens with low WBC counts (LW-mode). In the WBC differentiation channel and abnormal cell detection channel, optimization of the reagent reaction, signal processing, and analysis algorithms have improved the performance in cell differentiation as well as Schoorl_2013010053.indd 495 9/6/13 3:43 PM