A 5-year-old with classic PKU is on dietary management. Which statement about the PKU diet is correct?
- A Phenylalanine must be completely eliminated from the diet
- B Tyrosine supplementation is unnecessary because it is synthesized from phenylalanine
- C Phenylalanine is an essential amino acid and must be provided in small, measured amounts ✓
- D The diet can be safely discontinued after age 6 years
Correct answer: C. Phenylalanine is an essential amino acid and must be provided in small, measured amounts
Explanation
Phenylalanine is essential and cannot be synthesized de novo. Complete elimination would cause protein breakdown and deficiency. Small measured amounts (200 to 500 mg/day in young children) are required for growth. Tyrosine becomes conditionally essential because it cannot be made from phenylalanine. Lifelong dietary management is now recommended; discontinuing after age 6 is outdated practice.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.