NDT Advance Access originally published online on February 19, 2004
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Nephrol Dial Transplant (2004) 19: 1212-1223
Nephrol Dial Transplant Vol. 19 No. 5 © ERA-EDTA 2004; all rights reserved
Original Article
Effect of prescribing a high protein diet and increasing the dose of dialysis on nutrition in stable chronic haemodialysis patients: a randomized, controlled trial
1Divisions of Nephrology of the University Hospital Groningen, 2Martini Hospital Groningen, 3Scheper Hospital Emmen and 4University Medical Centre Utrecht, Groningen University Institute for Drug Exploration (GUIDE), The Netherlands
Correspondence and offprint requests to: R. M. Huisman, Department of Internal Medicine, Division of Nephrology, PO Box 30.001, 9700 RB Groningen, The Netherlands. Email: r.m.huisman{at}int.azg.nl
Background. Protein requirements in stable, adequately dialysed haemodialysis patients are not known and recommendations vary. It is not known whether increasing the dialysis dose above the accepted adequate level has a favourable effect on nutrition. The aim of this study was to determine whether prescribing a high protein diet and increasing the dose of dialysis would have a favourable effect on dietary protein intake and nutritional status in stable, adequately dialysed haemodialysis patients. Effects on hyperphosphataemia and acidosis were also studied.
Methods. Patients were randomized to a high dialysis dose (HDD) group (target Kt/Veq of 1.4) or a regular dialysis dose (RDD) group (target Kt/Veq of 1.0). All patients were prescribed a high protein (HP) diet [1.3 g/kg of ideal body weight (IBW)/day] and a regular protein (RP) diet (0.9 g/kg/day), each during 40 weeks in a crossover design. In 50 patients, 23 in the HDD and 27 in the RDD group follow-up was 
10 weeks. These patients, aged 56±15 years, were included in the analysis. Nutritional status was assessed by anthropometry, plasma albumin and a nutritional index.
Results. Delivered Kt/Veq in the HDD group (1.26±0.14) was significantly higher than in the RDD group (1.02±0.08). Protein intake estimated from total nitrogen appearance (PNA) measurements and food records (DPI) was significantly higher during the HP diet (PNAIBW, 1.01±0.18 g/kg/day; DPIIBW, 1.15±0.18 g/kg/day) than during the RP diet (PNAIBW, 0.90±0.14 g/kg/day; DPIIBW, 0.94±0.11g/kg/day). Increasing the dialysis dose did not increase protein intake either during the HP or RP diet. Plasma albumin (41.9±3.0 g/l) lean body mass (107±15% of normal values) and the nutritional index did not differ between the dialysis dose groups or protein diets and remained stable overtime. Dry body weight (97±14%) and total fat mass increased over time in the HDD group, but remained stable in the RDD group suggesting an effect of dialysis dose on energy balance. There was no effect of the protein diets on dry body weight or total fat mass. Plasma phosphate levels and oral bicarbonate supplements were lower in the HDD group, but were comparable between the protein diets.
Conclusions. Prescribing a HP diet resulted in a modest increase in actual protein intake, but increasing dialysis dose did not have a contributing effect. A HP diet or increasing the dialysis dose did not have a favourable effect on the nutritional status. A dietary protein intake of at least 0.9 g/kg IBW/day appears to be sufficient for adequately dialysed haemodialysis patients without overt malnutrition.
Keywords: dialysis dose; dietary protein intake; haemodialysis; Kt/V; nutritional status; protein diet; protein equivalent of total nitrogen appearance; prospective randomized study