The prospective, double blind randomized, parallel control, and multi-center clinical trial will evaluate the safety and efficacy of α-keto acid with restricted protein diet on protecting residual renal function in continuous ambulatory peritoneal dialysis (CAPD) patients.

Residual renal function (RRF) is associated with cardiovascular complication, nutritional status, incidence of peritonitis, and quality of life in peritoneal dialysis (PD) patients. Therefore, RRF is an important determinant of mortality and morbidity in PD patients.

Previous studies have suggested that dietary protein restriction supplemented with α-keto acids may slow the loss of RRF in chronic kidney disease patients. However, these trials are small sample and short-time research. In PD patients, there is very few reports to indicate the effect of α-keto acid with restricted protein diet on RRF.

The aim of this study is to evaluate the safety and efficacy of α-keto acid with restricted protein diet on protecting residual renal function in continuous ambulatory peritoneal dialysis (CAPD) patients.This is a prospective, double blind randomized, parallel control, and multi-center clinical study. 160 patients who meet Inclusion/Exclusion criteria will be randomized into α-Keto Acid group or control group at the ratio of 1:1. The α-Keto Acid group will use compound α-Keto Acid plus restricted protein diet, while control group will use placebo plus restricted protein diet.The α-Keto Acid dosage is 100mg/kg/d daily. The restricted protein dosage is 1g/kg/d. The safety and efficacy of α-Keto Acid with restricted protein diet on RRF will be evaluated after 1 year treatment.

Inclusion Criteria:

1. Patients on peritoneal dialysis (PD) at least three month prior to study entry.
2. Subjects of either sex, more than 18 years old, the range of age is 18 to 70 year old.
3. Residual GFR ≥ 3 ml/min/1.73m2.
4. Without α-Keto Acid therapy in recent 4 weeks.
5. Subjects who agree to participate in the study and sign the informed consent.

Exclusion Criteria:

1. History of peritonitis or other infection within one month.
2. Patients with insufficient dialysis.
3. History of taking drug which may influence amino acid metabolism within one month(glucocorticoid, thyroxin, antithyroid drug, androgens,amino acids,et al).
4. Patients with diseases which contraindicate ketosteril.
5. Cannot control diet according to protocol.
6. Alcohol abuse or drug abuse.
7. Having malignant tumor.
8. History of psychiatric or neuropathic dysfunction.
9. Cardiac failure, with New York Heart Association (NYHA) grade III-IV or history of severe heart and cerebrovascular disease in recent one month(acute stroke, acute heart failure, Lability angina)
10. Serum albumin < 30g/l.
11. Serum calcium > 2.8mmol/l.
12. Participation in another clinic trial within last three months