Overview
Introduction
Phenylketonuria (PKU) is an inherited disorder in which reduced phenylalanine hydroxylase activity prevents normal conversion of phenylalanine to tyrosine.
Phenylketonuria (PKU) is an inherited disorder in which reduced phenylalanine hydroxylase activity prevents normal conversion of phenylalanine to tyrosine. Phenylalanine therefore accumulates, while tyrosine becomes conditionally deficient. Without treatment, sustained elevation can injure the developing brain; excessive dietary restriction or overly effective medication can instead cause poor growth, protein catabolism, and developmental harm. The practical nurse keeps both risks in view. The treatment goal is a blood phenylalanine concentration of 120–360 micromol/L for life. Newborn screening identifies infants who need evaluation, but a screening result is not a diagnosis. Ongoing nursing care centers on prescribed medical food and diet adherence, growth and neurologic assessment, recognition of illness-related catabolism, medication safety, and prompt communication with the metabolic team.