Longitudinal urinary trace amine excretion in a human male.

The urinary excretion of a beta-phenylethylamine (PE), m-tyramine (mTA), p-tyramine (pTA) and tryptamine (TR) in their unconjugated (free) and conjugated (except tryptamine) forms, was examined in a male human subject over a total period of 28 days. The average excretion values were (in microgram per 24 h, mean +/- standard error): PE, free 3.19 +/- 0.21, conjugated 6.85 +/- 0.52, mTA, free 98.0 +/- 2.2, conjugated 106.1 +/- 18.6; pTA, free 427 +/- 12, conjugated 571 +/- 142; and TR, free 79.4 +/- 2.8. This data, when considered along with other published information, permits the suggestion that probably mTA and pTA in the unconjugated form are exclusively formed endogenously; whether or not this also pertains to PE and TR is less clear. In all cases, the conjugated amines derive from both exogenous and endogenous sources.