What screening is used after birth to detect inborn errors of metabolism?

• A. Newborn metabolic screening (heel-stick) for conditions like phenylketonuria and hypothyroidism
• B. Hearing screen
• C. Glucose tolerance
• D. Cord blood typing

Answer: (A)

Newborn metabolic screening using a heel-stick blood sample to detect inborn errors of metabolism is the test used after birth. It screens for conditions such as phenylketonuria and congenital hypothyroidism, among others. The sample, collected by a heel prick and dried on filter paper, is typically done after the baby has had a feeding and is about 24 hours old (policies vary). Early detection allows prompt treatment to prevent serious outcomes like neurodevelopmental problems or metabolic crises. Hearing screens check auditory function, not metabolic disorders; glucose tolerance tests assess how the body handles sugar (usually later in life or in pregnancy); cord blood typing determines blood type and Rh status, not metabolic conditions. Therefore, newborn metabolic screening is the appropriate postnatal screen for inborn errors of metabolism.