Intradialytic erythrocyte volume changes.

Haemodialysis (HD) should affect the erythrocytes, which constitute more than 99% of blood cells. The aim of this study was to reinvestigate the intradialytic changes in erythrocyte water content (MCV). MCV was measured during 81 HD (47 uncomplicated, 34 with hypotension), and 16 isolated ultrafiltrations (UF) performed in stable, haemodialysed adults (12 males and 8 females). The MCV following uncomplicated HD (n = 32) did not differ from the predialysis value. Significant MCV increase accompanied the HD initiation (4.9 +/- 9.0 fl, P less than 0.001), UF (2.99 +/- 1.49 fl, P less than 0.001) and hypotension (1.8 +/- 3.1 fl, P less than 0.01). This was independent of sodium and potassium within the cells and plasma. Erythrocyte oedema occurred in situations known to accompany both bioincompatibility reactions and blood volume decrease. Intradialytic MCV increase may reflect a response to these events, possibly hormonal, and needs further investigation.