A nurse is teaching a client who gave birth to a term newborn 24 hours ago about the newborn screening for phenylketonuria. Which of the following statements should the nurse include in the teaching?

Choice A reason: Newborn screening for phenylketonuria involves a heel stick blood test within 24-48 hours post-birth to detect elevated phenylalanine levels. Early testing ensures timely diagnosis, preventing intellectual disability from untreated phenylketonuria, a genetic disorder impairing phenylalanine metabolism, requiring immediate dietary intervention. Choice B reason: Lack of manifestations does not exempt newborns from phenylketonuria screening, as symptoms appear later. Screening is universal, as early detection prevents severe neurological damage from phenylalanine accumulation, making this statement incorrect for standard newborn care protocols. Choice C reason: Testing one week after birth delays phenylketonuria screening, risking untreated phenylalanine buildup, which causes irreversible brain damage. Screening occurs within 24-48 hours to ensure early intervention, making this timing incorrect for effective management of this metabolic disorder. Choice D reason: Fasting for 6 hours is not required for phenylketonuria screening. The heel stick test is performed regardless of feeding status, as phenylalanine levels are detectable early. Fasting risks hypoglycemia in newborns, making this an unnecessary and harmful requirement.