Automated reticulocyte counting using the Sysmex RAM-1

Reticulocyte counting using the Sysmex RAM-1 was evaluated. The results of 113 samples analysed on the Sysmex RAM-1 were compared with those from both flow cytometry (FCM) and a manual technique. Reticulocyte counting with the Sysmex RAM-1 showed excellent precision, with an overall coefficient of variance (CV) less than 5%, and almost no carry-over. Reticulocyte counts were stable after blood storage for 48 h at 4 degrees C and room temperature (RT). Linearity was demonstrated very well for Sysmex RAM-1 and FCM (rRAM=0.9998, rFCM=0.9974, P < 0.001) when reticulocyte counts were 5 x 109/l-480 x 109/l. Comparisons of methods showed a good relation for reticulocyte counts between Sysmex RAM-1 and manual counting (r=0.9760), FCM and manual counting (r=0.9623), and Sysmex RAM-1 and FCM (r=0.9527). Analysis of receiver operating characteristic curves showed that the true-positive rate (TPR) was 0.95 for Sysmex RAM-1, and 0.83 for FCM; the area under curve was 0.999 and 0.972 for Sysmex RAM-1, 0.990 and 0.900 for FCM. These findings confirm that Sysmex RAM-1 can make counting reticulocytes easier, more accurate and more reproducible.