A newborn screen reveals elevated phenylalanine (1200 µmol/L). Repeat confirmatory testing at 2 weeks confirms classic PKU. The dietary phenylalanine restriction should be maintained until:

• A Age 10 years when brain development is complete
• B Age 18 years
• C Until IQ testing confirms normal development at 5 years
• D Lifelong, especially for females of reproductive age ✓

Explanation

Current guidelines recommend lifelong phenylalanine-restricted diet in PKU; relaxation in adolescence is associated with neuropsychological deterioration. Crucially, women with PKU must maintain strict metabolic control before conception and throughout pregnancy to prevent maternal PKU syndrome (microcephaly, intellectual disability, cardiac defects in the offspring), even if the fetus is heterozygous. Stopping at age 10 or 18 is outdated practice associated with cognitive decline.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.