Reference values for new red blood cell and platelet parameters on the Abbott Diagnostics Cell-Dyn Sapphire

1 Department of Haematology UZ Brussel, Brussels , Belgium 2 Department of Medicine , UZ Brussel, Brussels , Belgium Keywords: ageing; normal values; red blood cells; reticulo-cytes; variability. A set of new parameters became available by the recent soft-ware upgrade (version 4) on the Cell-Dyn Sapphire haema-tology cell counter (Abbott Diagnostics, Santa Clara, CA, USA). Some of these parameters are linked with the size of red blood cells, such as the percentage of microcytic (pMIC) and macrocytic (pMAC) red blood cells. The percentage of hypochromic (pHPO) and hyperchromic (pHPR) erythro-cytes and haemoglobin distribution width (HDW) refl ect the haemoglobin (Hb) concentration of the cells. In addition, the mean corpuscular volume (MCVr), mean content of haemo-globin (MCHr) and concentration of haemoglobin (CHCr) of reticulocytes are measured. Finally, the percentage of reticulated platelets (pRP) is determined. Homologues of some of these parameters, determined on other analysers, have been shown to be clinically useful in the assessment of different conditions. In patients undergoing haemodialy-sis the European Best Practice Guideline uses pHPO and MCHr for assessment of anaemia due to iron defi ciency (1) . Although pHPO seems one of the best predictors of iron defi ciency (2) , the US Kidney Disease Outcomes Quality Initiative (KDOQI) only recommends MCHr because pHPO is very sensitive to ageing of the sample (3) , due to a swell-ing of the red blood cells. The impact of ageing seems to be different according to the technology used, as suggested for the percentage of hypochromic red blood cells by Buttarello et al. (4) . A rise of the percentage of reticulated plate-lets (pRP) precedes that of the platelet count after a bone marrow graft (5) . In this study, a complete peripheral blood count, includ-ing reticulocyte parameters, was performed on 151 healthy age of 26.0 years (interquartile range of 22.2 – 38.0). The large majority of the volunteers (144/151) were of Caucasian eth-nicity. Reference values were defi ned as the 2.5th and 97.5th percentiles of the results according to CLSI guidelines (6) . Outliers were removed when the difference with the median value exceeded at least 2.5 times the interquartile range. In addition we determined the reproducibility for these para-meters and studied the effect of ageing of the sample at room temperature on the test results. Reference values for a population of healthy adults are given in Table 1