Reference method for platelet counting and its application
Jiang Neng-gan · Chinese Journal of Laboratory Diagnosis · 2007
Objective To set up a reference method for platelet counting-the RBC/PLT ratio method.Methods Counting of specifically labeled platelets with CD41 and CD61 relative to the RBCs with a flow cytometer,together with an accurate RBC count determined with a semiautomated,single-channel aperture-impedance counter as a reference method for PLT counting;meanwhile,83 samples of daily whole blood of high,normal and low PLT values were collected and analyzed by the RBC/PLT ratio method as well as the methods of impedance,scatter and visual counting.Results The within-replicate coefficient of variance(CV) of the RBC/PLT ratio method was 1.5%,1.3%,13.3% for high count(760×109/L),middle count(130×109/L) and low count(8×109/L),respectively.Linearity was demonstrated well(r=0.9985) when the PLT count were 40×109/L-870×109/L.PLT count was stable at room temperature within 6 h.The carry-over was 0.19%.The results between the RBC/PLT ratio method and other methods of automated PLT counting including impedance or scatter methods were comparable(r0.98).The analysis of receive operating characteristic(ROC) for impedance or scatter methods compared with the RBC/PLT ratio method showed the performance of them was good,the area under curve(AUC) of impedance or scatter methods 0.99 and 0.98,respectively;and their sensitivity(Sen) was 100% and specificity(Spe) was 98% and 93.5%.However,the performance of visual PLT counting was not very good.Conclusion These findings confirm that the RBC/PLT ratio method for PLT counting is specific,accurate,precise,superior in linearity,lower in carry-over,could be as a reference method for PLT counting and as a candidate for evaluating other PLT counting methods.