Thirty-seven haemodialyses with ultrafiltration were performed (3000 ml/6 hours). using three sodium concentrations (140, 145 and 150 mmol/l) in the dialysate solution in 16 hyperhydrated patients during a long-term dialysis program. The amount of eliminated sodium during haemodialysis depended on the sodium concentration in the dialysate solution. The reduction of the volume of total body water corresponded to ultrafiltration. When a sodium concentration of 150 mmol/l in the dialysate solution was used, the smallest diminution of extracellular fluid and greatest diminution of intracellular fluid was observed. At the same time the greatest transport of water from the intracellular into the extracellular fluid was recorded. A sodium concentration of 145 and 150 mmol/l in the dialysate solution gave rise to positive values of sodium-free water and of sodium-free water clearance. Sodium-free water and of sodium-free water clearance correlated directly with the sodium concentration in the dialysate solution and inversely with the amount of eliminated sodium. The patients were free from complaints during haemodialyses and no significant blood pressure changes were found. The dialysate solution with the sodium concentrations used is suitable for a long-term dialysis programme; the authors recommend, however, to use individual sodium concentrations, depending on the patient's clinical condition.

Keywords: Adult; Body Water /metabolism/; Dialysis Solutions /analysis/; Female; Humans; Male; Renal Dialysis; Sodium /analysis/