Which statement is accurate regarding PKU screening in newborns?

B is the correct choice because a positive PKU screening indicates that the newborn has a heightened level of phenylalanine, suggesting that the infant may not be able to effectively metabolize this amino acid. This inability to process phenylalanine can lead to serious health issues, such as developmental delays and cognitive impairments, if not managed appropriately through dietary restrictions.

Infants with PKU require a special diet that limits phenylalanine intake. Therefore, the screening test is crucial, as early detection can lead to treatment that helps prevent neurological damage. This highlights the importance of newborn screening to identify metabolic disorders promptly.

The other statements do not accurately represent the outcomes of PKU screening: for instance, a negative result does not equate to the ability to tolerate all amino acids, and retesting may be needed if the first test is positive to confirm the diagnosis or monitor levels. Additionally, a negative result does not mean that infants can indiscriminately consume protein; dietary management is still important for their health.