Urinary p-cresol is elevated in small children with severe autism spectrum disorder

Biomarkers. 2011 May;16(3):252-60. doi: 10.3109/1354750X.2010.548010. Epub 2011 Feb 18.


Several studies have described in autistic patients an overgrowth of unusual gut bacterial strains, able to push the fermentation of tyrosine up to the formation of p-cresol. We compared levels of urinary p-cresol, measured by high-performance liquid chromatography-ultraviolet, in 59 matched case-control pairs. Urinary p-cresol was significantly elevated in autistic children smaller than 8 years of age (p < 0.01), typically females (p < 0.05), and more severely affected regardless of sex (p < 0.05). Urinary cotinine measurements excluded smoking-related hydrocarbon contaminations as contributors to these differences. Hence, elevated urinary p-cresol may serve as a biomarker of autism liability in small children, especially females and more severely affected males.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Analysis of Variance
  • Biomarkers / urine
  • Child
  • Child Development Disorders, Pervasive / diagnosis
  • Child Development Disorders, Pervasive / urine*
  • Child, Preschool
  • Cotinine / urine
  • Cresols / urine*
  • Diagnostic and Statistical Manual of Mental Disorders
  • Female
  • Humans
  • Male
  • Regression Analysis


  • Biomarkers
  • Cresols
  • 4-cresol
  • Cotinine