Urinary amine metabolite excretion in a patient with adrenergic hyperactivity state: reaction to phenelzine withdrawal and combined treatment.

Urinary MHPG (3-methoxy-4-hydroxyphenylglycol) amounts increased threefold during a toxic delirious state in a 57-year-old bipolar patient 3 days after phenelzine treatment was stopped. This norepinephrine metabolite was not expected to rise as monoamine oxidase (MAO) was completely blocked. In addition, the delirious state appeared as a rebound phenomenon and not an acute toxic state during drug administration. It seems that phenelzine acts more through catecholamine release phenomenon than by inhibition of MAO.