Amino acids are the basic structural units of proteins. Number of inborn errors of amino acid metabolism are known. These disorders result in the accumulation/ deficiency of one or more amino acids in the body, which causes clinical signs and symptoms of the particular amino acid disorder. This assay aids evaluation of patients with possible inborn errors of metabolism. It may, also, be used for evaluation of endocrine disorders, liver diseases, muscle diseases, neoplastic diseases, neurological disorders, nutritional disturbances, renal failure, and burns.