Ferrokinetics in Patients on CAPD: Influence of CAPD on the Anemia of Uremia(*)

Ferrokinetic studies were performed with (59)Fe-citrate to evaluate erythropoietic activity in CAPD patients and to investigate the mechanism(s) by which the hematocrit increases in CAPD patients. Plasma iron disappearance rate (PID), plasma iron turnover rate (PIT), red cell iron utilization (RCIU), red cell iron turnover rate (RCIT) and marrow transit time (MTT) were all “normal” in uremic patients not yet on dialysis (Hct 23.8±3.4%), CAPD patients with persistently low hematocrit (Hct 24.9±1.8%) and CAPD patients with improved hematocrit (Hct 32.4±3.1%). Compared to these uremic patients, patients with iron deficiency anemia and normal renal function (Hct 28.0±5.1 %) had significantly faster PID and MTT and significantly higher RCIU and RCIT. Plasma volume was significantly reduced (to normal level) in CAPD patients with improved hematocrits. The results of this study suggest that erythropoietic activity is inadequate for the degree of anemia in CAPD patients as well as uremic patients not on dialysis and further suggest that the hematocrit increases in CAPD as a result of decreased plasma volume.