Urinary excretion of 5-hydroxyindoleacetic acid, serotonin and 6-sulphatoxymelatonin in normoserotonemic and hyperserotonemic autistic individuals.
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.
Mulder
Erik J
EJ
Department of Child and Adolescent Psychiatry, University Medical Center Groningen, Groningen, The Netherlands. e.j.mulder @ accare.nl
Anderson
George M
GM
Kemperman
Ramses F J
RF
Oosterloo-Duinkerken
Alida
A
Minderaa
Ruud B
RB
Kema
Ido P
IP
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
C054513:6-sulfatoxymelatonin; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D003404:Creatinine; D008550:Melatonin