Final answer:
The nurse should interpret a serum phenylalanine level of 1 mg/dL (60.5 mcmol/L) as a positive result for phenylketonuria (PKU).
Step-by-step explanation:
The nurse should interpret a serum phenylalanine level of 1 mg/dL (60.5 mcmol/L) as a positive result. Phenylketonuria (PKU) is a metabolic disorder where individuals lack the enzyme phenylalanine hydroxylase, leading to a buildup of phenylalanine in the body. A normal serum phenylalanine level should be less than 1 mg/dL, so a level of 1 mg/dL indicates a positive result for PKU.