Phenylketonuria (PKU) Made Simple: An NCLEX One-Page Study Guide for Nurses
Think: “Musty smell + fair child + developmental delay = check for PKU.” What is Phenylketonuria (PKU)? Phenylketonuria (PKU) is a rare inherited metabolic disorder where the body cannot properly break down phenylalanine , an amino acid found in protein foods. Normally: Phenylalanine → (Phenylalanine Hydroxylase + BH4) → Tyrosine In PKU: The enzyme phenylalanine hydroxylase (PAH) is deficient Phenylalanine builds up in the blood Excess phenylalanine becomes toxic to the brain Tyrosine levels decrease → reduced melanin production NCLEX Keyword: Autosomal recessive disorder Why Does PKU Matter? Without early treatment, elevated phenylalanine can cause: 🧠Permanent neurological damage 🧠Developmental delay 🧠Intellectual disability 🧠Seizures This is why newborn screening is critical. Pathophysiology in One Minute Protein intake ↓ Phenylalanine cannot convert to tyrosine ↓ ↑ Phenylalanine accumulation ↓ Brain toxicity + ↓ melanin ↓ Neurological s...