Amino acids urinary loss

The determination of amino nitrogen before and after acid hydrolysis of urine has frequently been used for the quantitative estimation of the amount of urinary peptides (H5, M4). The number of liberated a-amino groups represents, in fact, the whole of formerly combined amino groups, not necessarily attached to a second amino acid partner. Besides, considerable losses connected with decomposition of some amino acids occur in the course of hydrolysis thus limiting the true quantitative value of this procedure. 

Alkaline supplement to the diet, urinary Ca loss, 76 Aluminum, effect on Ca metabolism, 162 Amino acids... 

Amino acids are precious components of the human organism and therefore urinary losses are small due to an efficient renal tubular reabsorption system. Because of this, and because the analytical approach is aimed at detecting catabolic... 

Age does not have a major influence on amino acid levels, with exception of the neonatal period. Premature babies may have underdeveloped hepatic and renal function, leading to increased tyrosine and methionine in their plasma as well as enhanced urinary losses of cystine, lysine, glycine, proline, hydroxyproline, and cystathionine. Taurine levels are generally increased in the first days of life. 

Hartnup disease is a rare genetic condition in which there is a defect of the membrane transport mechanism for tryptophan and other large neutral amino acids. The result is that the intestinal absorption of free tryptophan is impaired, although dipeptide absorption is normal. There is a considerable urinary loss of tryptophan (and other amino acids) as a result of the failure of the normal reabsorption mechanism in the renal tubules - renal aminoaciduria. In addition to neurological signs that can be attributed to a deficit of tryptophan for the synthesis of serotonin in the central nervous system, the patients show clinical signs of pellagra, which respond to the administration of niacin. 

The urinary contents also can provide important information concerning the presence of nephrotoxicity. The presence or elevated levels of enzymes, protein, amino acids, glucose, blood, or casts in the urine can signal renal injury. Enzymuria results primarily from the loss of the brush border (microvilli)... 

Another indication of the relevance of the Maillard reaction to human nutrition and metabolism was the finding of urinary loss of bound amino acids after infusion of autoclaved sugar (glucose or finctose)—amino acid or peptide solutions. Nonutilizable amino acids were detected in the blood and urine (S38, S39). After these and other reports, parenteral solutions were sterilized by nonheat methods. 

Sulfur has an antagonistic effect on several essential trace elements. Excessive amounts of sulfur can induce a secondary deficiency of copper (mainly in animals), cobalt and selenium. Ho vever, not only the sulfur amino acid cysteine but also sulfate eliminates the adverse effects of copper-, cobalt-or selenium-based toxicities (Baker and Czarnecki-Maulden 1987). Sulfate increases the urinary loss of selenate, but not of selenite this explains the assumption that there is a direct antagonism between sulfate and selenate (Schrauzer 1998). 

Effect on Protein Metabolism, Corticoid hormones affect various steps of protein metabolism amino acid penetration in the cells, intracellular biosynthesis of amino acids from small precursors, protein synthesis, and protein catabolism. In discussing the effect of corticoid hormones on protein synthesis, it is necessary to distinguish between the effects of the glucocorticoid on muscle and liver. The injection of Cl 1-oxygenated corticosteroid increases the excretion of urinary nitrogen, with loss of tissue nitrogen (e.g., in heart and kidney) [51]. 

Cystine. As previously noted, the cystine poor diet failed to give conclusive N-balance results. Measurements of the cystine output during the deficiency period showed a gradual fall in the urinary cystine which rose to above normal levels on restoration of the amino acid to the diet (134). These findings might be taken to suggest that a lack of dietary cystine is not completely compensated by methionine and that some loss of tolerance to cystine was induced by the deficiency. 

A condition in which abnormally large amounts of amino acids are excreted in the urine. This disorder is usually due to one or more defects in the processes by which the kidneys prevent such urinary loss. 

Protein. Dietary protein increases the rate of calcium absorption from the small intestine. The probable explanation of this phenomenon is that the amino acids, especially lysine and arginine, liberated in the course of protein digestion, form soluble calcium salts which are easily absorbed. But any advantage from increased absorption will likely be more than counterbalanced by the increas urinary loss of calcium on high-protein diets. 

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