Background: Optical analysis of erythrocytes can provide information on the hemoglobin concentration and content of reticulocytes and mature erythrocytes. Such parameters have proven clinical utility in anemia diagnosis and therapy monitoring. For interpretation, reliable reference ranges are needed. The aim of this study was to establish reference intervals for extended erythrocyte and reticulocyte parameters as measured with the Abbott CELL-DYN Sapphire hematology analyzer. Secondary aims were to study sample stability and to investigate gender- and age dependency of the reference ranges.
Methods: Extended RBC parameters were measured in routine samples of a primary health care laboratory. The study cohort included 8161 samples of unique individuals, which were analyzed using Bhattacharya statistics. As a comparison, reference intervals were calculated in a subset of individuals without iron depletion.
Results: The majority of erythrocyte and reticulocyte parameters were normally distributed, allowing calculation of reference intervals. Only for hypo- and hyperchromic erythrocytes non-parametric statistics had to be used. The reference range for mean cellular hemoglobin content of reticulocytes (MCHr) was 28.5-34.5 pg (1.77-2.14 fmol) in the entire study group and 26.0-35.1 pg (1.60-2.17 fmol) in the non iron-depleted subgroup. No differences between sexes were found. Most parameters showed significant age effects in children and adolescents.
Conclusions: Reference intervals have been established for extended RBC and reticulocyte parameters for the CELL-DYN Sapphire. Gender effects could not be demonstrated and age effects were of limited size, except for individuals younger than 18 years. Extended RBC parameters are stable for at least 6 h after blood collection.