Aminoaciduria occurs when the urine contains abnormally high amounts of amino acids. 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.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. [Source: Wikipedia 
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