Question

When preparing to obtain a neonatal screening test for phenylketonuria (PKU), the nurse understands that the neonate must have been fed what to ensure reliable results?

a-a feeding of an iron-rich formula
b-nothing by mouth for 4 hours before the test
c-initial formula or breast milk at least 24 hours before the test
d-a feeding of glucose water

Answer 1

For reliable neonatal screening test results for PKU, the neonate must have ingested initial formula or breast milk at least 24 hours before the test since the presence of phenylalanine from these nutrients is necessary for accurate metabolic assessment.

Step-by-step explanation:

When preparing to obtain a neonatal screening test for phenylketonuria (PKU), the nurse understands that the neonate must have consumed initial formula or breast milk at least 24 hours before the test to ensure reliable results. This is because the test involves measuring the neonate's ability to metabolize phenylalanine, which is present in breast milk and formula.

Phenylketonuria (PKU) is a condition where the individual lacks sufficient activity of the enzyme phenylalanine hydroxylase and cannot adequately break down phenylalanine into tyrosine. As a result, levels of phenylalanine can rise to toxic levels, leading to damage to the central nervous system and brain. Therefore, it is critical that the neonate has ingested a source of phenylalanine, such as breast milk or formula, to provide an accurate assessment of the neonate's metabolic capabilities.