What is a pku done on the babay and what happens if it comes back abnormal?

Newborn screening: Pku is a label often applied to the newborn screening program that has gone on for the last 50 years or so in some form throughout the states.Any + for any of the tests(~34 in texas)requires that a specific confirmatory test be done to see if the screening was a false + or a real problem. I usually hear about a + screen a week after the test & bring in the kid for testing & discussion.