Figure 1833

Amino acid (AA) solutions for parenteral nutrition in acute renal failure (ARF). The most controversial choice regards the type of amino acid solution to be used: either essential amino acids (EAAs) exclusively, solutions of EAA plus nonessential amino acids (NEAAs), or specially designed "nephro" solutions of different proportions of EAA and specific NEAA that might become "conditionally essential" for ARF (see Fig. 18-11).

Use of solutions of EAA alone is based on principles established for treating chronic renal failure (CRF) with a low-protein diet and an EAA supplement. This may be inappropriate as the metabolic adaptations to low-protein diets in response to CRF may not have occurred in patients with ARF. Plus, there are fundamental differences in the goals of nutritional therapy in the two groups of patients, and consequently, infusion solutions of EAA may be sub-optimal.

Thus, a solution should be chosen that includes both essential and nonessential amino acids (EAA, NEAA) in standard propor tions or in special proportions designed to counteract the metabolic changes of renal failure ("nephro" solutions), including the amino acids that might become conditionally essential in ARF.

Because of the relative insolubility of tyrosine in water, dipep-tides containing tyrosine (such as glycyl-tyrosine) are contained in modern nephro solutions as the tyrosine source [22, 23]. One should be aware of the fact that the amino acid analogue N-acetyl tyrosine, which previously was used frequently as a tyrosine source, cannot be converted into tyrosine in humans and might even stimulate protein catabolism [21].

Despite considerable investigation, there is no persuasive evidence that amino acid solutions enriched in branched-chain amino acids exert a clinically significant anticatabolic effect. Systematic studies using glutamine supplementation for patients with ARF are lacking (see Fig. 18-11).

0 0

Post a comment