Role of sodium and water in hypertensive patients on maintenance hemodialysis.

In 46 patients of the chronic hemodialysis program blood pressure regulation was studied according to variations of sodium and fluid balance. A strong relationship was observed between blood pressure and the amount of exchangeable sodium. In the hypertensive patients exchangeable sodium was increased depite fulfilled clinical signs of sufficient dehydration. The blood volume was found to be small and the plasma renin activity increased in those hypertensive patients, in which sufficient fluid depletion was inhibited by extreme fluctuations of the blood pressure during dialysis. A diminution of the sodium concentration keeping the fluid balance constant induced an increase of blood pressure and deteriorated the subjective feeling of the patients. By an increase of the sodium concentration up to 155 mEq/l severe blood pressure fluctuations during during dialysis could be prevented, although further fluid was taken off by ultrafiltration. This effect seemed to be mediated--at least partly--by an increase of the low blood volume and a suppression of plasma renin activity. After the patients became normotensive, dialysis procedure could be continued with normal sodium concentration. By a temporary high sodium regimen of the dialysis procedure some patients with renal failure and 'uncontrollable hypertension' can be preserved from bilateral nephrectomy.