AMINO ACIDS in free form in the plasma are filtered through the glomerulus with almost complete tubular reabsorption (Fig 1). Aminoaciduria is a common finding in the majority of normal individuals accounting for 1% to 2% of the total urinary nitrogen excretion. The term aminoaciduria is commonly interpreted as the urinary excretion of one or more amino acids in quantities greater than normal or the excretion of certain amino acids or intermediates of amino acid metabolism not normally found in the urine or both.
Various classifications of aminoaciduria exist which involve terminology such as physiologic, primary or secondary, congenital or acquired, prerenal and renal, and combinations of the preceding. One classification based on the presumed or proven pathogenesis is as follows.
Overflow or Prerenal Aminoaciduria. The increased urinary excretion of amino acids is regarded as a consequence of elevated plasma amino acid levels. The increased plasma values may be