A nurse in the nursery is preparing to perform phenylketonuria (PKU) testing. Which neonate is ready for the nurse to test ？（）
A．A 3-day-old neonate who has been fed IV since birth.
B．A 2-day-old neonate who has been breast-fed.
C．A 1-day-old neonate receiving formula.
D．A breast-fed neonate being discharged within 24 hours of birth.
参考答案：B
解析：
To test for PKU, a neonate must have had a sufficient intake of phenylalanine through the ingestion of either formula or breast milk for at least 2 days. A neonate who has been receiving IV fluids and hasn't yet received breast milk or formula isn't ready to be tested for PKU. A neonate who is discharged within 24 hours of delivery will need to see the physician for PKU testing after receiving formula or breast milk for 48 hours.