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PhenylketonuriaAka: PKU

See Also
1. Inborn Errors of Metabolism
Epidemiology
1. Incidence: 1:15000
Pathophysiology
1. Autosomal-recessive disorder
2. Phenylalanine hydroxylase gene mutation
  1. Enzyme converts phenylalanine to tyrosine
  2. Phenylalanine concentrations rise with mutation
3. Phenylalanine threshold for adverse effects >20 mg/dl
Symptoms
1. Irritability
Signs: Complications on unrestricted diet
1. Head Circumference small for age (Microcephaly)
2. Cognitive delay
3. Light skin pigmention
Labs
1. Identified on Newborn Screen
Management
1. Strict low phenylalanine diet for life
  1. Infant: Low Phenylalanine formula
  2. Pregnancy: Monitor phenylalanine concentrations
2. Supplementation
  1. Tyrosine 25 mg/kg/day
  2. Amino acid dosing
    1. Infant: 3 g/kg/day
    2. Child: 2 g/kg/day
References
1. Raghuveer (2006) Am Fam Physician 73:1981

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