Protein intake and the nutritional status in patients with pre-dialysis chronic renal failure on unrestricted diet

Malnutrition is known to be highly associated with morbidity and mortality in dialysis patients. Malnutrition may begin to develop in patients with chronic renal failure(CRF) before they need dialysis. In this study, the nutritional status of patients with moderate to severe CRF on unrestricted diet was evaluated.

We measured dietary protein intake (DPI, g/kg/day) in 64 patients with CRF and 42 normal controls(N). Nutritional indices such as serum albumin(SA, g/dl), transferrin(TF, mg/dl), prealbumin(PA, mg/dl) and insulin-like growth factor-1(IGF-1, ng/ml) were measured to evaluate the visceral proteins, and creatinine-height index(C-H, g/d/m) to evaluate the somatic proteins.

Mean DPI was 0.80 +/- 0.27(S.D) in CRF and 1.07 +/- 0.30 in N(p < 0.0001). DPI was lower than 0.6 in 15 CRF patients(23%). Serum albumin, transferrin and C-H were significantly lower in CRF patients than in N(p < 0.01). In patients with CRF, nutritional indices were significantly worse with lower DPI(< 0.6 g/kg/d, n = 15) than higher DPI(> 0.6 g/kg/d, n = 49)(SA 2.9 +/- 0.7 vs. 3.6 +/- 0.8, p < 0.005; TF 147 (134-179) vs. 220(182-264), p < 0.0005; PA 24 +/- 8 vs. 32 +/- 9, p < 0.001; IGF-1 123 (66-261) vs. 226(140-344), p < 0.05; C-H 0.52 +/- 0.15 vs. 0.87 +/- 0.23, p < 0.0001). CRF patients with nephrotic range proteinuria (> 3.5 g/d, n = 19) had lower SA (2.8 +/- 0.6 vs. 3.8 +/- 0.8, p < 0.0001) and PA(27 +/- 9 vs. 32 +/- 9, p < 0.05). CRF patients with diabetes mellitus (n = 20) showed worse nutrition than non-diabetic patients(SA 2.8 +/- 0.6 g/dl vs. 3.8 +/- 0.8 g/dl, p < 0.0001; TF 176 mg/dl(148-214) vs. 220 mg/dl(175-266), p < 0.05; PA 24 +/- 10 mg/dl vs. 33 +/- 8 mg/dl, p < 0.0005; IGF-1 138 ng/ml(69-269) vs 231 ng/ml(140-364), p < 0.05; C-H 0.66 +/- 0.23 vs. 0.85 +/- 0.5, p < 0.005).

A significant protein malnutrition prevails in patients with pre-dialysis CRF on unrestricted diet, especially with low protein intake. The effort to detect and correct malnutrition should be made in patients with CRF even before initiation of maintenance dialysis.