Rheological red blood cell properties in morbidly obese and super obese patients.

In a recent paper by Wiewiora et al. published in this Journal [7], the authors observed that superobese patients (BMI >50 kg/m2) show erythrocyte rheological differences when compared with morbidly obese patients (BMI >40 kg/m2). In this sense, although they did not observe differences in erythrocyte deformability using the LORCA device, they found a higher erythrocyte aggregation index (AI10), a shorter erythrocyte aggregation time (Ta) and a higher erythrocyte disaggregation threshold ( D) in superobese patients when compared with morbidly obese ones. This greater tendency of erythrocytes to aggregate does not seem to be related with either plasmatic lipids or fibrinogen levels, and the authors have no explanation for this feature. To further clarify this issue, we analyzed the rheological red blood cell properties in morbidly obese patients from a previous published study [6] by evaluating erythrocyte aggregation (AI10, Ta, D) and erythrocyte deformability (EI) at 12, 30 and 60 Pa [2, 4, 5], along with biochemical, inflammatory and haematological parameters in 54 morbidly obese subjects and 27 superobese subjects, who were ageand sex-matched qualified for bariatric surgery. Table 1 shows the differences in the several parameters analysed. Superobese subjects showed higher glucose levels, and AI10 (P= 0.030; P= 0.012, respectively), lower Ta and D (P= 0.026; P= 0.007, respectively). Pearson’s bivariate correlation (Table 2) showed the correlations between erythrocyte aggregation and the other parameters analysed. In the morbidly obese, D correlated directly with fibrinogen (P< 0.01), but with haematimetric indices MCV and MCH (P< 0.05) in the superobese. The results of the present study indicate that superobese patients showed a higher AI10 and, correspondingly, a lower Ta, which is in agreement with Wiewiora et al. However, D was lower than in the morbidly obese subjects, indicating that the cohesion force of the rouleaux formed was lower than in the morbidly obese subjects, which is in disagreement with Wiewiora et al. [7]. This surprising fact may