Is anaemia during continuous ambulatory peritoneal dialysis really better than during haemodialysis?

The level of anaemia in 22 patients on continuous ambulatory peritoneal dialysis (CAPD) was compared with that in 12 patients maintained on intermittent haemodialysis. Contrary to previous reports, the haematocrit did not differ between these groups, nor did it increase progressively with time in those on CAPD. Total red cell volume (RCV) and plasma volume were also similar in the two groups. Clearance of radioactive iron from plasma (plasma iron turnover) was higher in haemodialysis than in CAPD patients but erythrocyte radioiron utilisation (FeU) did not differ in the two groups. RCV in both CAPD and haemodialysis patients correlated positively with erythrocyte iron turnover and FeU but not with red cell survival, suggesting that the rate of production rather than destruction of red cells is the major determinant of total RCV in dialysis patients. Red cell survival was slightly but significantly higher in CAPD than in haemodialysis patients and increased with time on dialysis, but this difference was insufficient to increase total RCV in CAPD patients above that in haemodialysis patients.