Shortly after birth, a blood sample is taken from a newborn to screen for diseases such as phenylketonuria (PKU) and congenital hypothyroidism. This type of testing is important because treatment is available to improve the health of the child. Newborn screening is required in the United States, but states vary on which tests they offer.
Examples of tests used for newborn screening include:
Phenylketonuria (PKU) screening, which tests for phenylalanine in a baby's blood. Babies found to have PKU should be put on a special low-protein diet to prevent mental retardation.
Newborn screening for cystic fibrosis. Levels of immunoreactive trypsinogen (IRT), a digestive enzyme, are measured from a blood sample. Abnormally high levels of IRT suggest CF, although further testing is needed to confirm the