In chronic uremia (CRF), malnutrition is an important determinant of morbid
ity in adults and impaired growth in children. Causes of malnutrition inclu
de anorexia and abnormal protein and amino acid metabolism. To determine ho
w different levels of dietary protein and CRF interact to influence growth
and nutritional status, CRF and sham-operated, pair-fed control rats were f
ed isocaloric diets containing 8, 17, or 30% protein for 21 d to mimic diet
ary regimens recommended for CRF patients: the minimum daily requirement; t
he recommended daily allowance; or an excess of dietary protein. Serum crea
tinine did not differ between groups of CRF rats but blood urea nitrogen wa
s lowest in CRF rats fed 8% protein (P < 0.001). CRF rats eating 30% protei
n gained less weight and length compared to their controls or CRF rats fed
8 or 17% protein (P < 0.05); they also had acidemia. CRF rats fed 8% protei
n had the highest efficiency of utilization of protein for growth, while 17
% protein promoted the highest efficiency of utilization of food and calori
es for growth. Notably, CRF rats eating 30% protein had the lowest protein
efficiency; their calorie intake was also the lowest because of anorexia. P
lasma branched-chain amino acids were progressively higher in control rats
eating 8, 17, or 30% protein. CRF rats fed 8 or 17% protein had lower branc
hed-chain amino acid concentrations compared with CRF rats fed 30% protein.
In CRF, it is concluded that excessive dietary protein impairs growth but
a law-protein diet does not impair nutritional responses and permits utiliz
ation of protein for growth if calories are sufficient.