title: Urinary excretion of 5-hydroxyindoleacetic acid, serotonin and 6-sulphatoxymelatonin in normoserotonemic and hyperserotonemic autistic individuals.
abstract: OBJECTIVE
  A substantial proportion of individuals with autism have elevated levels of platelet serotonin (5-HT). We examined whether platelet hyperserotonemia is associated with increased gut 5-HT synthesis, altered 5-HT catabolism or altered melatonin production.
  
  
  METHODS
  Urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA) and 5-HT was compared in 10 normoserotonemic and 10 hyperserotonemic age-matched autistic individuals. The relationship of urinary 6-sulfatoxymelatonin (6-SM) excretion to platelet 5-HT, and to urinary 5-HT and 5-HIAA excretion, was also examined.
  
  
  RESULTS
  In the hyperserotonemic group, significant increases at trend level in urinary excretion of 5-HIAA (p = 0.061) and 5-HT (p = 0.071) and a significant decrease for 6-SM were found (p = 0.027). The urinary 5-HIAA:5-HT ratio was similar in the normo- versus the hyperserotonemic groups.
  
  
  CONCLUSIONS
  The catabolism of 5-HT does not differ in the groups, but greater exposure of the platelet to 5-HT cannot be ruled out as a cause of the platelet hyperserotonemia of autism. Although only trend level significant, the data point to a need for larger studies to examine more thoroughly the relationships between platelet hyperserotonemia, gut 5-HT synthesis and melatonin production.
authors.affiliation: Department of Child and Adolescent Psychiatry, University Medical Center Groningen, Groningen, The Netherlands. e.j.mulder @ accare.nl
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Mulder
authors.forename: George M
authors.initials: GM
authors.lastname: Anderson
authors.forename: Ramses F J
authors.initials: RF
authors.lastname: Kemperman
authors.forename: Alida
authors.initials: A
authors.lastname: Oosterloo-Duinkerken
authors.forename: Ruud B
authors.initials: RB
authors.lastname: Minderaa
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001321:Autistic Disorder / Q000097:blood* / Q000652:urine*; D003404:Creatinine / Q000652:urine; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000652:urine*; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine; D012701:Serotonin / Q000097:blood* / Q000652:urine*; D014364:Tryptophan / Q000097:blood
chemical_list: C054513:6-sulfatoxymelatonin; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D003404:Creatinine; D008550:Melatonin