NDT Advance Access published online on March 3, 2009
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfp085
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Better preservation of residual renal function in peritoneal dialysis patients treated with a low-protein diet supplemented with keto acids: a prospective, randomized trial
1 Renal Division, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai Center for Peritoneal Dialysis Research 2 Nutritional Division, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China 3 Divisions of Baxter Novum and Renal Medicine, Department of Clinical Science, Intervention, and Technology, Karolinska Institutet, Stockholm, Sweden
Correspondence and offprint requests to: Qiang Yao; E-mail: qiang_yao{at}baxter.com
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Abstract |
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Background. While a low-protein diet may preserve residual renal function (RRF) in chronic kidney disease (CKD) patients before the start of dialysis, a high-protein intake is usually recommended in dialysis patients to prevent protein-energy wasting. Keto acids, which were often recommended to pre-dialysis CKD patients treated with a low-protein diet, had also been reported to be associated with both RRF and nutrition maintenance. We conducted a randomized trial to test whether a low-protein diet with or without keto acids would be safe and associated with a preserved RRF during peritoneal dialysis (PD).
Methods. To assess the safety of low protein, we first conducted a nitrogen balance study in 34 incident PD patients randomized to receive in-centre diets containing 1.2, 0.9 or 0.6 g of protein/kg ideal body weight (IBW)/day for 10 days. Second, 60 stable PD patients [RRF 4.04 ± 2.30 ml/ min/1.73 m2, urine output 1226 ± 449 ml/day, aged 53.6 ± 12.8 years, PD duration 8.8 (1.5–17.8) months] were randomized to receive either a low- (LP: 0.6–0.8 g/kg IBW/day), keto acid-supplemented low- (sLP: 0.6–0.8 g/kg IBW/day with 0.12 g/kg IBW/day of keto acids) or high-protein (HP: 1.0–1.2 g/kg IBW/day) diet. The groups were followed for 1 year and RRF as well as nutritional status was evaluated serially.
Results. A neutral or positive nitrogen balance was achieved in all three groups. RRF remained stable in group sLP (3.84 ± 2.17 to 3.39 ± 3.23 ml/min/1.73 m2, P = ns) while it decreased in group LP (4.02 ± 2.49 to 2.29 ± 1.72 ml/min/1.73 m2, P < 0.05) and HP (4.25 ± 2.34 to 2.55 ± 2.29 ml/min/1.73 m2, P < 0.05). There was no change from baseline on nutritional status in any of the groups during follow-up.
Conclusions. A diet containing 0.6–0.8 g of protein/kg IBW/day is safe and, when combined with keto acids, is associated with an improved preservation of RRF in relatively new PD patients without significant malnutrition or inflammation.
Keywords: chronic kidney disease; diet; glomerular filtration rate; malnutrition; nitrogen balance
Received for publication: 28. 9.08
Accepted in revised form: 10. 2.09