[Automated hematology analysers and spurious counts Part 3. Haemoglobin, red blood cells, cell count and indices, reticulocytes]

Abstract

Several situations lead to abnormal haemoglobin measurement or to abnormal red blood cells (RBC) counts, including hyperlipemias, agglutinins and cryoglobulins, haemolysis, or elevated white blood cells (WBC) counts. Mean (red) cell volume may be also subject to spurious determination, because of agglutinins (mainly cold), high blood glucose level, natremia, anticoagulants in excess and at times technological considerations. Abnormality related to one measured parameter eventually leads to abnormal calculated RBC indices: mean cell haemoglobin content is certainly the most important RBC parameter to consider, maybe as important as flags generated by the haematology analysers (HA) themselves. In many circumstances, several of the measured parameters from cell blood counts (CBC) may be altered, and the discovery of a spurious change on one parameter frequently means that the validity of other parameters should be considered. Sensitive flags allow now the identification of several spurious counts, but only the most sophisticated HA have optimal flagging, and simpler ones, especially those without any WBC differential scattergram, do not share the same capacity to detect abnormal results. Reticulocytes are integrated into the CBC in many HA, and several situations may lead to abnormal counts, including abnormal gating, interference with intraerythrocytic particles, erythroblastosis or high WBC counts.