Phenylketonuria PKU

  • Facts:
    Autosomal recessive condition, where there is a deficiency in phenylalanine hydroxylase (breaks down phenylalanine into tyrosine), leading to accumulation of phenylalanine

    Patients appear normal at birth, but manifest characteristic features during infancy
  • History / PE:
    Urine has musty odor (from phenylacetic acid)
    Fair skin, blue eyes, eczema
  • Diagnosis:
    Elevated phenylalanine blood levels ( > 20mg/dL)
    Guthrie test (qualitative, coloration test)
    Normal tetrahydrobiopterin (confirm diagnosis)
  • Treatment:
    Low phenylalanine diet
    Avoid high protein foods
  • Complications:
    Mental retardation
  • Notes:
    Guthrie test detects the metabolic products of phenylalanine in the urine
  • Differential Diagnosis:
    1) Benign hyperphenylalaninemia (mildly elevated phenylalanine)
    2) Transient hyperphenylalaninemia (asymptomatic)
    3) Tyrosinemia (babys smell like boiled cabbage)
    4) Alkaptonuria (homogentisic acid in urine)

Review Edit Entry New Entry

August 7th 2010