Erythrocyte deformability in anaemic patients with reticulocytosis determined by means of ektacytometry techniques

Abstract

It is not clearly established whether reticulocyte deformability is lower than that of the mature erythrocytes, as most of studies published on this matter have evaluated this rheological parameter by means of micropipette techniques, which are unsuitable for routine measurements. Information is scarce as regards the evaluation of reticulocyte deformability by means of ektacytometry techniques, routinely used in clinical laboratories. We aimed to evaluate erythrocyte deformability (ED), with ektacytometry, in samples of 44 anaemic patients with peripheral reticulocytosis (reticulocytes: (260±150)×10³/μl) and in 60 healthy non-anaemic volunteers with a normal reticulocyte count (reticulocytes: (60±20)×10³/μl). We also determined other factors that may influence ED, such as erythrocyte indices (MCV, MCH, MCHC), glucose, total cholesterol and triglycerides. ED was evaluated determining the elongation indices (EI) at 12, 30 and 60 Pa, by means of the Rheodyn SSD. At the three shear stresses tested, patients showed statistically lower EI than controls, higher reticulocyte count, lower cholesterol levels and higher MCHC (P<0.001, respectively). A statistically significant negative correlation (P<0.01) was found between the reticulocyte count and the EI at 12, 30 and 60 Pa (r=−0.643, r=−0.678 and r=−0.692, respectively), and between the EI and the MCHC (correlation coefficients: −0.743, −0.741 and −0.738; P<0.01). As the differences in ED could be attributed partly to alterations in erythrocyte indices and plasma lipid levels, a linear regression analysis was performed, showing that EI is independently associated with the reticulocyte count. Our results suggest that reticulocytes are responsible for the decreased ED observed in anaemic patients with peripheral reticulocytosis, when this hemorheological parameter is evaluated by means of ektacytometry techniques.