Dietary management of chronic renal failure with oral amino acids

Effects of dietary protein and phosphorus restriction on the progression of chronic renal failure

In recent years, evidence has accumulated suggesting that early dietary intervention in the form of protein restriction can dramatically alter the natural history of chronic renal insufficiency. This article reviews the literature in this area and summarizes the questions that remain for future investigators to answer. Interest in the role of protein intake in renal disease dates back to the early 1900s, when several investigators found that the progression of renal failure was accelerated in rats and rabbits fed high-protein diets. Subsequent work in animal models has demonstrated that nephron loss, resulting from a variety of disease states, is associated with elevated intraglomerular pressures and flows. Several investigators now have postulated that these abnormal hemodynamics, resulting from intrarenal vasodilation and hyperperfusion, damage the glomerulus and may produce further nephron loss independent of the initial renal insult. Dietary protein restriction appears to reduce these pressures and flows towards normal in animals, although the operative mechanism has yet to be identified. Limited studies of dietary protein restriction in human renal disease have suggested a beneficial effect, but carefully controlled prospective studies will be necessary to establish clear therapeutic efficacy.

Changes in serum calcium caused by supplementation of low protein diets with keto-acid analogues in patients with chronic renal failure

Six patients with stable end stage chronic renal failure have been studied while receiving keto-acid supplements that provided a daily calcium load of 42 +/- 2 mM. None of the patients had intercurrent illness. All patients showed elevated serum calcium concentration levels while on keto-acid supplements, reaching significance on 5 occasions. Reciprocal falls in serum phosphate concentrations were noted in all patients, and this observation was not due to an anabolic effect of the keto-acids. In 3 patients, the rise in serum calcium concentration was associated with marked clinical manifestations that required curtailment of treatment. The risk of hypercalcemia occurs early and certain high risk categories can be identified. Recommendations about the use of calcium salts of alpha-keto-acid analogues are given and it is suggested that a choice should be made available between calcium and sodium salt analogues.