Urinary acid metabolites of biogenic amines in schizophrenic patients

A hypothesis is presented that only pure type B monoamine oxidase (MAO) amine substrates and their oxidized metabolites should be altered in mental patients, especially paranoid chronic schizophrenics. If urinary pH is rigorously controlled, it is predicted that 24-hour urinary amine levels (free and total) of pure type B MAO substrates will be elevated and their corresponding acid metabolites reduced, especially under excess substrate conditions in vivo. The usual 50 percent decrease in platelet MAO, which is reported to be in some schizophrenic patients in vitro, should especially show biochemical functional deficits in vivo when the organism is stressed with a suitable amine or amino acid substrate given as a diagnostic load. Such an approach amy be useful in demonstrating a functional biochemical deficit and the biological significance of low platelet MAO activity (a type B MAO) seen in some psychiatric patients.