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The role of nutrition in the growth retardation of children with chronic renal failure undergoing maintenance dialysis Rothney, Linda Mary


Growth failure is a major problem in children with chronic renal failure (CRF). A number of factors have been suggested as explanations for this impaired growth including renal osteodystrophy, age of onset of chronic renal failure, degree of azotemia and nutritional status. As children with CRF are frequently unable to maintain sufficient nutrient intakes for optimal growth, the nutritional status of these individuals must obviously have a major, if as yet poorly understood, role in the observed growth failure. Therefore, a nutritional, physical and biochemical study was conducted to assess the nutritional status of seven children undergoing maintenance hemodialysis. To evaluate the adequacy of dietary intake, fourteen day food records were obtained from each of the participants and average nutrient intakes were compared to the recommended daily nutrient intake of the Canadian Dietary Standard (CDS) (1975). To assess the physical status of the children, height, height velocity, weight, per cent body fat, and bone age were determined. As abnormalities of taste sensitivity are known to influence dietary patterns, salivary flow rates, salivary urea concentrations, and taste detection and recognition thresholds for sweet, sour, salt and bitter were determined pre and post dialysis. Biochemical investigations included the determination of pre and post dialysis plasma amino acid concentrations following a standardized fast of five hours, and the quantification of the amounts of amino acids lost into dialysate during a complete hemodialysis treatment. The mean caloric intake of 54% ±11 of the CDS is inadequate for optimal growth. The mean protein intake was 1.09 ±.16 grams of protein per kilogram of body weight. The first and second limiting amino acids were histidine and threonine, respectively. Nutritional deficiencies of certain water soluble vitamins (riboflavin, niacin and pyridoxine) existed for some of the children. The mean zinc, magnesium and copper intakes were 45% ±8, 51% ±19 and 54% ±32 of the CDS, respectively. Growth (as measured by body height and weight) was found to be retarded one to two standard deviations from normal in the children studied. Per cent body fat estimations were within normal limits, but bone age was frequently below chronological age. Taste sensitivity was impaired as shown by elevated pre dialysis sweet and bitter recognition thresholds (p<.01). This reduced taste acuity was improved post dialysis (p<.005), but did not reach normal values. Pre and post dialysis, salivary flow rates were reduced (p<.0005) and salivary urea concentrations elevated (p<.0005) when compared to normal. Pre dialysis, plasma concentrations of taurine, a-amino-butyric acid, valine, cystine, leucine, tyrosine and tryptophan were decreased from normal levels (p<.025), and aspartic acid, proline, glycine, citrulline, ornithine, histidine, arginine, asparagine, 3-methylhistidine and hydroxyproline were elevated above normal (p<.005). The presence of subclinical protein calorie malnutrition (PCM) was indicated by a depressed plasma essential to nonessential amino acid ratio, a depressed plasma valine to glycine ratio, and an elevated plasma phenylalanine to tyrosine ratio as compared to normal. The detection of 3-methylhistidine and hydroxyproline in plasma provides additional indications of PCM. The mean amount of total amino acid lost into dialysate was 4.7 ±.9 grams. Histidine, threonine, lysine and valine were the essential amino acids lost in the largest amounts. In conclusion, growth is retarded in children with CRF and may be due to the accumulation of metabolic end products which depress appetite and/or delay the natural rate of growth events Suboptimal nutriture, as evidenced by the presence of PCM, is a major factor in the growth retardation of these individuals.

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