Abnormal results Definition Amino acid disorder screening checks for inherited disorders in amino acid metabolism. Tests are most commonly done on newborns. Two tests are available, one using a blood sample and the other a urine sample. Purpose Amino acid disorder screening is done in newborns, and sometimes children and adults, to detect inborn errors in metabolism of amino acids. Twenty of the 100 known amino acids are the main building blocks for human proteins.
Proteins regulate every aspect of cellular function.
Of these 20 amino acids, ten are not made by the body and must be acquired through diet. Screening is especially important in newborns. Some congenital amino acid metabolic defects cause mental retardation that can prevented with prompt treatment of the newborn. This is an genetic error in metabolism of phenylalanine, an amino acid found in milk. Individuals with PKU do not produce the enzyme necessary to break down phenylalanine.