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
Examples of tests used for newborn screening
Cystic fibrosis test.
Levels of immunoreactive trypsinogen (IRT), a digestive enzyme, are measured
from a newborn's blood sample. Abnormally high levels of IRT suggest cystic fibrosis,
although further testing is needed to confirm the diagnosis.
Other tests, such as newborn
hearing tests, can tell whether a baby may need future
hearing services or genetic testing. Approximately 50% of cases of newborn
hearing loss are caused by genetic factors.1