Effect of Protein-Restricted Diet on Nitrogen Balance and Residual Renal Function in Peritoneal Dialysis (PD) Patients

Effect of Protein-Restricted Diet on Nitrogen Balance and Residual Renal Function in PD Patients

Current therapy recommendations suggest a low protein diet to preserve residual renal function (RRF) before the start of dialysis, but a higher protein intake during dialysis to prevent protein-energy wasting (PEW). We conducted a randomized trial to test whether low protein intake also during treatment with peritoneal dialysis (PD) would be safe and associated with a preserved RRF.

Dietary protein is the major source of nitrogen excreted as urea by the kidney, and a decreased protein intake has been associated with a retardation of kidney function loss in non-dialysis chronic kidney disease (CKD) patients. While a low protein diet is recommended to end-stage renal disease (ESRD) patients before the start of dialysis to preserve residual renal function(RRF), current therapy recommendations in dialysis are for a normal protein intake of no less than 1.2 g of protein/kg ideal body weight (IBW)/day to prevent protein-energy wasting (PEW).

We hypothesized that a lower protein intake would be safe and able to slow the loss of RRF also in dialysis patients and conducted two prospective, randomized trials involving a total of 94 peritoneal dialysis (PD) patients to test our hypothesis.

Inclusion Criteria:

• age 18-80 years
• stable peritoneal dialysis since at least 1 month
• with renal function

Exclusion Criteria:

• a high probability (assessed by the recruiting physician) of receiving a kidney transplant within one year
• overt infection within the last month
• poor compliance in previous dietary prescriptions or irregular check-ups
• persistent anorexia, vomiting or diarrhea within the last month
• a CRP of more than 30 mg/dL
• presence of wasting diseases such as cancer or tuberculosis