Urinary p-tyramine in hereditary tyrosinemia: I. Levels as compared to normal individuals, effect of diet, and relationship to urinary tyrosine.

1. A 40-fold increase in urinary p-tyramine was observed in a patient with hereditary tyrosinemia as compared to a control population. 2. The excretion of urinary-free p-tyramine was decreased with the restriction of oral phenylalanine and tyrosine in this patient. The pattern of urinary tyrosine and urinary-free p-tyramine was similar during the period of normal protein diet and restricted diet of phenylalanin and tyrosine. 3. The pattern of urinary-free p-tyramine and tyrosine following oral loads of tyrosine and phenylalanine was similar except for a lag period before a tyramine response was observed. 4. The possibility of the patient with hereditary tyrosinemia providing a model to study the origin of urinary p-tyramine is discussed.