The Optimal Protein Intake in Patients with Early Chronic Renal Failure

The effects of a low-protein diet on the serum insulin-like growth factor (IGF)-1 and IGF binding proteins (IGFBP) were investigated during a 3-month controlled study in 12 adult chronic renal failure patients. Six patients were randomly supplemented with keto acids (Cetolog, Clintec, Velizy, France). Protein intake was prescribed so that both groups were isonitrogenous. Dietary survey included a monthly 3-day food record and a 24-h urinary urea measurement. After a 4- to 6-wk equilibrium period (1.11 g of protein, 32 kcal/kg body wt per day), patients reduced their protein intake to 0.71 g protein/kg body wt per day. Energy intake was kept constant (31 kcal/kg body wt per day) during the 3-month period. Serum IGF-1 levels were in normal range and, for 11 of the 12 patients, were correlated with the GFR (P = 0.01). These serum IGF-1 values did not decrease after reducing the protein intake. By Western ligand blotting, serum IGFBP1, IGFBP2, and IGFBP4 levels were significantly higher than normal adults, whereas the IGFBP3 level was not increased. IGFBP were not modified when protein intake was reduced. The IGFBP1 level was elevated despite a normal insulin level. IGFBP4 changes were inversely correlated with IGF-1 variations. There was no difference between groups receiving or not receiving the keto acids. Thus, in adult chronic renal failure, reducing protein intake by 40% did not modify the growth hormone/IGF-1/IGFBP axis.

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Spontaneous dietary protein intake during progression of chronic renal failure.

Journal of the American Society of Nephrology ◽

10.1681/asn.v651386 ◽

1995 ◽

Vol 6 (5) ◽

pp. 1386-1391

Author(s):

T A Ikizler ◽

J H Greene ◽

R L Wingard ◽

R A Parker ◽

R M Hakim

Keyword(s):

Renal Failure ◽

Chronic Renal Failure ◽

Dietary Protein ◽

Protein Intake ◽

Mixed Model ◽

Dietary Protein Intake ◽

Nutritional Indices ◽

Igf I ◽

Progression Of Renal Failure ◽

The Mean

Malnutrition at the initiation of dialysis is a strong predictor of subsequent increased mortality on dialysis. Few studies have documented the relationship between the progression of renal failure and spontaneous dietary protein intake (DPI) and other indices of malnutrition. In this prospective study, renal function was sequentially measured by creatinine clearance (CrCl) and DPI by 24-h urine collection; simultaneously, multiple sequential biochemical nutritional indices, including serum albumin, transferrin, prealbumin, and insulin-like growth factor-I (IGF-I) concentrations, were measured. The study involved 90 patients (46 men and 44 women) with chronic renal failure (CRF) of various causes monitored in an outpatient clinic. Dietary interventions were minimal. The mean duration of follow-up was 16.5 +/- 11.8 months. The results show that the mean (+/- SD) DPI was 1.01 +/- 0.21 g/kg per day for patients with CrCl over 50 mL/min and decreased to 0.85 +/- 0.23 g/kg per day for patients with CrCl between 25 and 50 mL/min. The DPI further decreased to a level of 0.70 +/- 0.17 g/kg per day for patients with CrCl between 10 and 25 mL/min and was 0.54 +/- 0.16 g/kg per day for patients with CrCl below 10 mL/min. This trend was statistically significant (P < 0.001). A similar statistically significant trend was observed for serum cholesterol, transferrin, and total creatinine excretion (all P < 0.01). A mixed model analysis indicated that for each 10 mL/min decrease in CrCl, DPI decreased by 0.064 +/- 0.007 g/kg per day, transferrin decreased by 16.7 +/- 4.1 mg/dL, weight decreased by 0.38 +/- 0.13% of initial weight, and IGF-I decreased by 6.2 +/- 1.9 ng/mL. It was concluded that the progression of renal failure is associated with a spontaneous decrease in DPI, especially below a CrCl of 25 mL/min, and that most nutritional indices in CRF patients worsen as CrCl and DPI decrease. Dietary protein restriction should be used cautiously in CRF patients when CrCl falls below 25 mL/min.

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