IS IT POSSIBLE TO CONTROL HYPERPHOSPHATEMIA WITH DIET, WITHOUT INDUCING PROTEIN-MALNUTRITION

Dietary intervention, phosphate (P) removal during dialysis and, espec ially, phosphate binders are current methods for the management of hyp erphosphataemia. Ideally, the amount of P absorbed from the diet shoul d equal the amount of P removed during dialysis, and this must occur i n the context of an adequate protein intake. We evaluated the relation ship between P intake and protein intake in 60 stable chronic uraemic patients (mean age 55 +/- 15 years, 25% diabetics, 68% males) on stand ard 4 h haemodialysis. The dietary counselling was relatively free for protein and calories. Nutrient intake was recorded during a 5 day per iod, and average daily ingestion of P and proteins was calculated usin g a computerized diet analysis system. A highly significant correlatio n was observed between protein and P intake. The mean daily ingestion of P and proteins was 998 +/- 316 mg and 64 +/- 19 g (1 +/- 0.4 g/kg/d ay), respectively. For an optimal protein diet of 1-1.2 g/kg/day, the P intake was 778-1444 mg. The amount of P removed by haemodialysis, ex trapolated to an average week, is 250-300 mg/day. Since similar to 40% of P ingested is absorbed from the gut by uraemic patients treated wi th intestinal P binders, 750 mg of P intake should be the critical val ue above which a positive balance of P may occur. This value correspon ds to a protein intake of 45-50 g per day (>0.8 g/kg body weight/day f or a 60 kg patient). In patients undergoing standard chronic haemodial ysis, a neutral P balance is difficult to achieve, despite phosphate b inder therapy, when protein intake is > 50 g. Additional protein restr iction, in order to obtain a neutral balance, may impose the risk of p rotein malnutrition.