Newborn screening uses blood tests to detect treatable genetic, metabolic, and hematologic disorders in newborns. These disorders can hinder development if not diagnosed early. The first screening tests for phenylketonuria were developed in the 1960s, and screening has since expanded to include over 30 disorders. Blood is collected via a heel prick and tested using techniques like tandem mass spectrometry that can screen for multiple disorders from a single sample. If abnormalities are detected, specialists evaluate and treat the infant as needed.