Aminoaciduria occurs when the

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

contains abnormally high amounts of

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

s. In the healthy kidney, the glomeruli filter all amino acids out of the blood, and the

renal tubule The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure ...

s then reabsorb over 95% of the filtered amino acids back into the blood. In overflow aminoaciduria, abnormally high concentrations of amino acids in the

blood plasma Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but which contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up ...

overwhelm the resorptive capacity of the renal tubules, resulting in high concentrations of amino acids in the urine. This may be caused by congenital disorders of amino acid metabolism, for example,

phenylketonuria Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also r ...

, or may be secondary to

liver disease Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common. Liver diseases File:Ground gla ...

. 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. This may be caused by a defect in the

transport protein A transport protein (variously referred to as a transmembrane pump, transporter, escort protein, acid transport protein, cation transport protein, or anion transport protein) is a protein that serves the function of moving other materials within ...

s in the renal tubule, for example, as occurs in

Hartnup disease Hartnup disease (also known as " pellagra-like dermatosis" and "Hartnup disorder") is an autosomal recessive metabolic disorder affecting the absorption of nonpolar amino acids (particularly tryptophan that can be, in turn, converted into se ...

, or may be due to damage to the kidney tubule, for example, as occurs in

Fanconi syndrome Fanconi syndrome or Fanconi's syndrome (, ) is a syndrome of inadequate reabsorption in the proximal renal tubules of the kidney. The syndrome can be caused by various underlying congenital or acquired diseases, by toxicity (for example, from t ...

References

External links

{{Amino acid metabolic pathology Abnormal clinical and laboratory findings for urine