Affiliations: Department of Internal Medicine, Free University Hospital, P.O.Box 7057, 1007 MB Amsterdam, The Netherlands
Note: [] Accepted by: Editor F. Mahler
Abstract: A recently recommended method supposedly estimating the mechanical properties of unmanipulated erythrocytes, was tested in our laboratory in various groups of subjects. Blood was spun for 15 minutes at 200×G (Ha15) and for 5 minutes at 12000×G (Ht). The difference between the obtained hematocrit values Ha15 and Ht, the “erythrocyte packing difference” (EPD), was expressed as a percentage of the hematocrit Ht (%EPD=[(Ha15–Ht)/Ht]× 100). Fifty-two healthy volunteers (N), thirty-seven diabetics (DM) and thirty-five patients with intermittent claudication (IC) were tested. No differences in EPD could be found between N and DM (N: %EPD=23.7±3.1%, DM: %EPD=22.9±3.1%, mean ± SD). In the IC-group EPD was significantly lower compared to both other groups (IC: %EPD=16.2±2.6%, p < 0.01 vs N and vs DM). The EPD and %EPD in the IC-group correlated inversely with plasma fibrinogen concentration (r = −0.710, p < 0.001 and r = −.0784, p < 0.001, respectively) and with plasma viscosity (r = −.0694, p < 0.001 and r = −0.781, p < 0.001, respectively). We therefore suggest that the EPD is not a method which can be recommended for routine use as a measure for mechanical properties of erythrocytes. Plasma properties (plasma viscosity and plasma fibrinogen concentration) do appear to play a major role in the EPD. Thus, it might be possible that the EPD is more a measure of alterations in plasma viscosity c.q. fibrinogen concentration than of changes in intrinsic erythrocyte deformability.
