Amino Acid Medical Foods Provide a High Dietary Acid Load and Increase Urinary Excretion of Renal Net Acid, Calcium, and Magnesium Compared with Glycomacropeptide Medical Foods in Phenylketonuria Introduction PKU (PKU; OMIM 261600) is an inherited metabolic disorder characterized by high Phe concentrations in blood due to mutations in the gene which encodes phenylalanine hydroxylase (PAH; EC 1.14.16.1). PAH catalyzes...