State law requires newborn screening be done when the baby is 72 hours old or prior to discharge, whichever comes first. The law also requires a follow-up screen between 3 and 7 days of age, if the first was done within 24 hours of birth. The American Academy of Pediatrics also recommends a subsequent newborn screen for babies whose first screen was within 24 hours of birth. But it's a good thing for parents to be aware of also. PKU is a very rare disease, affecting only one in every 15,000 newborns.
Dietary changes can change the course of the disease and prevent mental retardation.
Missing even one case would be unacceptable. Early discharge from the hospital also affects the diagnostic sensitivity of tests for maple syrup urine disease and homocystinuria.