THE SPUN MICRO-HEMATOCRIT AND MEAN RED-CELL VOLUME ARE AFFECTED BY CHANGES IN THE OXYGENATION STATE OF RED-BLOOD-CELLS

in this study we examined the effects of in vitro oxygenation and deox ygenation on the spun micro-haematocrit (packed cell volume or PCV) an d the electronically measured mean cell volume (MCV) and haematocrit ( Hct) of red blood cells. Because PCV and/or MCV and Hct are being used for calibration of haematology analysers, it is important that their potential variability caused by outside factors is known, We found tha t these parameters did vary with the oxygenation state of the erythroc yte and conclude that the effect is most likely caused by a combinatio n of water shifts due to intracellular carbamate and bicarbonate forma tion, and conformational changes in haemoglobin, The results of the st udy have implications for whole blood calibration and for short term i mprecision assessments of automated haematology analysers. To ensure c onsistent results, we recommend that blood specimens be fully oxygenat ed before reference work or reproducibility studies of MCV, Hct and/or PCV are attempted.