Should protein intake be restricted in predialysis patients?

There are also no data supporting the second assumpIn the last decade, two findings have cast doubt on tion, with the obvious exception of starting dialysis in the wisdom of administering low-protein diets to CRF severely uremic patients. The third assumption is also patients: First, a large body of evidence has documented unsupported by the literature: Protein nutrition of CRF that hypoalbuminemia in dialysis patients is a major risk patients is usually maintained or improved by low-profactor for mortality, whether present at the onset of tein or supplemented very low protein diets. Hence, a dialysis or developed during dialysis [4‐19]. Other indi- well-planned, low-protein diet not only maintains or imces of nutritional status, such as urea nitrogen appear- proves nutritional state (including serum albumin levels) ance and predialysis levels of creatinine and cholesterol, in predialysis patients, but by reducing symptoms, it also are also correlated with mortality [4‐19]. Second, the delays the need for dialysis. Moreover, substantial evihypothesis that protein restriction slows the progression dence suggests that it may also slow the rate of progresof CRF (another rationale for its use) has not been un- sion of renal insufficiency. equivocally confirmed (discussed later here). As a result The benefits of a nutritional regimen include the folof these findings, some workers have questioned the lowing: (a) reduction in (or delayed onset of) symptoms wisdom of restricting protein intake [20‐22]. Further- and signs of uremia; (b) forestalling complications by more, they have suggested that if spontaneous protein lowering the accumulation of waste products at any given intake falls below 0.8 g/kg/day, patients are at increased level of glomerular filtration rate (GFR); and (c) perhaps risk of malnutrition, and the appropriate response is to slowing the rate of decline of GFR. Objections that have start dialysis unless protein intake can be increased. The been raised include cost, poor compliance, and perhaps assumptions underlying these recommendations are that: the increased risk of malnutrition. In this article, we (a) protein nutrition will improve in predialysis patients review the evidence supporting each of these benefits, if protein intake increases; (b) dialysis improves dietary as well as the evidence for each of these objections. intake and nutritional status; and (c) low protein intake causes malnutrition in predialysis patients.