INSULIN-LIKE GROWTH-FACTOR-I AND ITS BINDING-PROTEINS DURING A LOW-PROTEIN DIET IN CHRONIC-RENAL-FAILURE

The effects of a low-protein diet on the serum insulin-like growth fac tor (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(R), Clintec, Velizy, France). Protein intake was prescribed so that both g roups were isonitrogenous, Dietary survey included a monthly 3-day foo d record and a 24-h urinary urea measurement. After a 4- to 6-wk equil ibrium period (1.11 g of protein, 32 kcal/kg body wt per day), patient s reduced their protein intake to 0.71 g protein/kg body wt per day. E nergy 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 W estern ligand blotting, serum IGFBP1, IGFBP2, and IGFBP4 levels were s ignificantly higher than normal adults, whereas the IGFBP3 level was n ot 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. T hus, in adult chronic renal failure, reducing protein intake by 40% di d not modify the growth hormone/IGF-1/IGFBP axis.