The neglect of sodium restriction in dialysis patients: a short review.

In end-stage renal failure, natriuresis decreases, sodium accumulates, and extracellular volume (ECV) excess develops. In 1962, Scribner, reporting about the first maintenance hemodialysis (HD) patient, observed that ECV control using a low-salt diet and ultrafiltration led to blood pressure (BP) normalization. Thus, the concept of dry weight, the ideal postdialysis weight allowing for a stable normal BP, was born. Achieving dry weight requires a combination of negative diffusive sodium balance, adequate ultrafiltration, and a low-salt diet. Unfortunately, the low-salt diet is very often neglected today. In the late 1960s, BP control was achieved in 90% of HD patients using low-sodium dialysis and a low-salt diet. As time passed and HD duration was reduced, there was a worsening BP control and subsequent increasing in morbidity and mortality. In recent years, interventional studies have examined the effects of reducing sodium in dialysate, in diet, or in both. All of them show that low-salt diet is essential for BP control in HD. While the healthy population is advised to eat a reasonably low-salt diet (5 g of NaCl), the K/DOQI Guidelines and the European Best Practice Guidelines surprisingly do not even mention salt restriction. To achieve dry weight under the present conditions, with short HD duration and a frail population, it is mandatory to reduce the interdialytic weight gain. A low-salt diet is, more than ever, a necessity.