ABSTRACT
Although dietary protein restriction may protect against progression of renal failure, it is important to consider whether protein restriction can be attained without inducing malnutrition. We assessed the calculated dietary protein intake(cDPI) by 24 hour urinary collection and food intake, biochemical nutritional indices and the results of anthropometric measurement in 83 predialysis patients with different stages of chronic renal failure(CRF) and 84 controls. Dietary interventions were minimal. We categorized patients into three groups according to whether their creatinine clearance(Ccr) was greater than 25(group A), 10 to 25(group B), or less than 10ml/min(group C). 1) The mean(+/-SD) cDPI was significantly lower in group C(0.77+/-0.17g/kg/day) and group B(0.84+/- 0.16g/kg/day) than in group A(1.04+/-0.21g/kg/day) and controls(1.14+/-0.22g/kg/day)(P<0.05). The mean (+/-SD) high biologic value protein intake was significantly lower in group C(0.29+/-0.25g/kg/day) and group B(0.39+/-0.27g/kg/day) than in group A (0.48+/-0.35g/kg/day)(P<0.05). The cDPI(r=0.50, P< 0.05), high biologic value protein intake(r=0.39, P< 0.05) were positively correlated with the Ccr. 2) The mean (SD) total lymphocyte count (TLC) was significantly lower in group C(1,554+/-368/mm3) and group B(1,972+/-470/mm3) than in group A(2,111+/-540/mm3) and controls(2,177+/-589/mm3)(P<0.05). The TLC was positively correlated with the Ccr(r= 0.28, P<0.05). The levels of albumin and transferrin were lower in patients with CRF than in controls (P<0.05). There was no difference in the levels of albumin, transferrin, prealbumin, insulin-like growth factor-1, cholesterol and anthropometric measurements among the different stages of CRF. CONCLUSION: In predialysis patients with CRF, the dietary protein and high biologic value protein intake spontaneously decreases as renal function declines. Several nutritional indices, such as TLC, albumin and transferrin were lower in predialysis patient with CRF than controls. Therefore objective measurement of DPI should be considered to educate a low protein diet in predialysis patients with CRF.