Final answer:
Routine screening for PKU in newborns is done using a urine test. If the urine turns emerald green after adding a 10% FeCl3 solution, it indicates the presence of PKU. Early detection helps in managing the condition through a modified low-phenylalanine diet.
Step-by-step explanation:
Routine screening for phenylketonuria (PKU) in newborns is done through a urine test. A 10% FeCl3 solution is added to the baby's fresh urine, and if the urine turns emerald green, it indicates the presence of PKU. This color fades after 20 minutes. PKU is a genetic disorder where individuals lack sufficient activity of the enzyme phenylalanine hydroxylase, leading to elevated levels of phenylalanine in the body. Early detection through newborn screening allows for the implementation of a modified diet low in phenylalanine to prevent symptoms and damage.