A review of candidate urinary biomarkers for autism spectrum disorder

Context: Autism is a complex, heterogeneous neurodevelopmental condition with a strong genetic component potentially impacted by various environmental factors influencing susceptibility. There are no reliable laboratory tests available to confirm an autism diagnosis. Objective: To examine the published literature and identify putative urinary biomarkers of autism. Methods: A comprehensive literature search was conducted using electronic bibliographic databases. Results: Putative autism biomarkers were identified that could be categorized according to the key theories that exist regarding the etiology of autism: gastrointestinal factors, immune dysregulation, heavy metal toxicity, neurotransmitter abnormalities, and oxidative stress. Conclusion: There is scope for specific urinary biomarkers to be useful for identification of autistic metabolic phenotypes.