CHANGES IN PARTITION OF EXTRACELLULAR FLUID VOLUMES IN ANEMIC DIALYZED UREMIC PATIENTS AFTER PARTIAL CORRECTION OF THE ANEMIA WITH RECOMBINANT-HUMAN-ERYTHROPOIETIN TREATMENT

The purpose of this work was to study the effects of correcting anemia on the distribution and partition of body fluids in dialyzed uremic s ubjects. We studied nine (7 m, 2 f) patients before and three months a fter the start of i.v. treatment with rHu-EPO, measuring total body wa ter (TBW) with (H2O)-H-2, extracellular fluid volume (ECFV) with (SO4) -S-35 and plasma volume (PV) with I-125-SA. The intracellular water (I CW) and the interstitial fluid volumes (IFV) were derived by calculati on from those measurements. The total blood volume (TBV) was calculate d from the PV and the packed cell volume (PCV). Mean TBW, 482 +/- 45 ( M +/- SD) ml/kg/bw and ECFV, 168 +/- 27.5 ml were significantly lower in patients than in nine matched normal controls, while the mean ICW ( 315 +/- 43 ml/kg) was similar. PCV before the start of rHu-EPO was 17. 2 +/- 2.9% and had risen significantly to 31.3 +/- 4.8% (p = 0.000) af ter three months of therapy. Body weight (58 +/- 13 kg), TBW, ECFV and ICW did not change. TBV before rHU-EPO was 68.7 +/- 7.5 ml/kg and rem ained nearly unchanged, while PV fell significantly from 57 +/- 9 to 4 8 +/- 8 ml/kg (p < 0.025), with the calculated IFV rising from 111 +/- 25 to 127 +/- 27 (p = 0.000). The PV/IFV ratio decreased from 0.53 +/ - 0.12 to 0.38 +/- 0.09 (p = 0.001). The decrease in PV/IFV ratio was paralleled by simultaneous increase in PCV in all but one patient. The se findings point to the key role of the intravascular erythrocyte mas s in regulating the partition of the ECFV and in determining the exten t of the hydration of the interstitial fluid compartment of chronic ur emic patients.