Aminoaciduria

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Aminoaciduria
Other namesUrine amino acids [1]
Amino acids in food and blood.png
Share of amino acid in various human diets and the resulting mix of amino acids in human blood serum. Glutamate and glutamine are the most frequent in food at over 10%, while alanine, glutamine, and glycine are the most common in blood.
Complications Severe protein loss in the blood
Risk factors Liver disease, malnutrition, kidney disease

Aminoaciduria occurs when the urine contains abnormally high amounts of amino acids. [2] In the healthy kidney, the glomeruli filter all amino acids out of the blood, and the renal tubules then reabsorb over 95% of the filtered amino acids back into the blood. [3]

In overflow aminoaciduria, abnormally high concentrations of amino acids in the blood plasma overwhelm the resorptive capacity of the renal tubules, resulting in high concentrations of amino acids in the urine. [4] This may be caused by congenital disorders of amino acid metabolism, [3] for example, phenylketonuria, [5] or may be secondary to liver disease. [3]

In renal aminoaciduria, the renal tubules are unable to reabsorb the filtered amino acids back into the blood, causing high concentrations of amino acids in the urine. [5] This may be caused by a defect in the transport proteins in the renal tubule, for example, as occurs in Hartnup disease, [5] or may be due to damage to the kidney tubule, for example, as occurs in Fanconi syndrome. [4]

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<span class="mw-page-title-main">Proteinuria</span> Presence of an excess of serum proteins in the urine

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<span class="mw-page-title-main">Cystinosis</span> Lysosomal storage disease

Cystinosis is a lysosomal storage disease characterized by the abnormal accumulation of cystine, the oxidized dimer of the amino acid cysteine. It is a genetic disorder that follows an autosomal recessive inheritance pattern. It is a rare autosomal recessive disorder resulting from accumulation of free cystine in lysosomes, eventually leading to intracellular crystal formation throughout the body. Cystinosis is the most common cause of Fanconi syndrome in the pediatric age group. Fanconi syndrome occurs when the function of cells in renal tubules is impaired, leading to abnormal amounts of carbohydrates and amino acids in the urine, excessive urination, and low blood levels of potassium and phosphates.

<span class="mw-page-title-main">Hartnup disease</span> Metabolic disorder

Hartnup disease is an autosomal recessive metabolic disorder affecting the absorption of nonpolar amino acids. Niacin is a precursor to nicotinamide, a necessary component of NAD+.

<span class="mw-page-title-main">Metabolic alkalosis</span> Medical condition

Metabolic alkalosis is a metabolic condition in which the pH of tissue is elevated beyond the normal range (7.35–7.45). This is the result of decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate concentrations. The condition typically cannot last long if the kidneys are functioning properly.

<span class="mw-page-title-main">Renal tubular acidosis</span> Medical condition

Renal tubular acidosis (RTA) is a medical condition that involves an accumulation of acid in the body due to a failure of the kidneys to appropriately acidify the urine. In renal physiology, when blood is filtered by the kidney, the filtrate passes through the tubules of the nephron, allowing for exchange of salts, acid equivalents, and other solutes before it drains into the bladder as urine. The metabolic acidosis that results from RTA may be caused either by insufficient secretion of hydrogen ions into the latter portions of the nephron or by failure to reabsorb sufficient bicarbonate ions from the filtrate in the early portion of the nephron. Although a metabolic acidosis also occurs in those with chronic kidney disease, the term RTA is reserved for individuals with poor urinary acidification in otherwise well-functioning kidneys. Several different types of RTA exist, which all have different syndromes and different causes. RTA is usually an incidental finding based on routine blood draws that show abnormal results. Clinically, patients may present with vague symptoms such as dehydration, mental status changes, or delayed growth in adolescents.

<span class="mw-page-title-main">Dent's disease</span> Medical condition

Dent's disease is a rare X-linked recessive inherited condition that affects the proximal renal tubules of the kidney. It is one cause of Fanconi syndrome, and is characterized by tubular proteinuria, excess calcium in the urine, formation of calcium kidney stones, nephrocalcinosis, and chronic kidney failure.

<span class="mw-page-title-main">Renal glycosuria</span> Medical condition

Renal glycosuria is a rare condition in which the simple sugar glucose is excreted in the urine despite normal or low blood glucose levels. With normal kidney (renal) function, glucose is excreted in the urine only when there are abnormally elevated levels of glucose in the blood. However, in those with renal glycosuria, glucose is abnormally elevated in the urine due to improper functioning of the renal tubules, which are primary components of nephrons, the filtering units of the kidneys.

<span class="mw-page-title-main">Urine test strip</span> Diagnostic tool used in urinalysis

A urine test strip or dipstick is a basic diagnostic tool used to determine pathological changes in a patient's urine in standard urinalysis.

References

  1. "Aminoaciduria". Medline. NIH. Retrieved 18 March 2019.
  2. "Aminoaciduria". Mosby's Medical Dictionary (9th ed.). Mosby. 2013. p. 79. ISBN   9780323112581.
  3. 1 2 3 Schück, O (1984). "Amino acids excretion. Physiology and pathophysiology". Examination of Kidney Function. Translated by Cort, JH. Dordrecht: Springer Netherlands. p. 252. ISBN   9789400956605.
  4. 1 2 Crook, Martin Andrew (2012). "Chapter 27: Inborn errors of metabolism". Clinical biochemistry and metabolic medicine (8th ed.). London: Hodder Arnold. pp. 371–383. ISBN   9781444144154.
  5. 1 2 3 Mundt, LA; Shanahan, K (2011). "Chapter 7: Urinary and metabolic diseases and related urinalysis findings. Aminoacidurias". Graff's textbook of routine urinalysis and body fluids (2nd ed.). Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins Health. pp. 203–210. ISBN   9781582558752.