Serotonin metabolism and other biochemical parameters in infantile autism. A controlled study of 22 autistic children.

The serotonin metabolism was extensively studied in 22 couples of autistic children and age- and sex-matched controls. Histamine, calcium, and uric acid were also measured in urine and whole blood or plasma. Autistics and controls did not differ in histamine, and only minor changes were noticed in calcium content. According to previous reports, serotonin levels were often, but not always, elevated in the blood of autistic children. Based on data including urinary serotonin and 5-hydroxyindoleacetic acid, platelet serotonin uptake and efflux, platelet monoamine oxidase and glutathione peroxidase activities, and uric acid and plasma tryptophan, the origin(s) of such hyperserotonemia in autism appear(s) to be of metabolic origin, i.e., a decreased catabolism and/or an increased biosynthesis of serotonin.