Urinary excretion of amines in phenylketonuria and mongolism.

Children with phenylketonuria excrete considerably less serotonin and tryptamine and somewhat less normetanephrine and p-tyramine than normal children. The excretion of these amines was not decreased in mongolism. Even during monoamine oxidase blockade, o-tyramine could not be detected in the urine of phenylketonurics. These findings are discussed in relation to the mental defect of phenylketonuria.