Disordered porphyrin metabolism: a potential biological marker for autism risk assessment.
Urine porphyrin levels run high in some kids with autism, but the test misses too many cases to stand alone.
01Research in Context
What this study did
The team collected urine from kids with autism and from typical kids. They measured two porphyrin molecules: penta and coproporphyrin. The goal was to see if these levels could flag autism risk.
What they found
Kids with autism had much higher levels of both porphyrins. The test was good at ruling autism in when levels were high, but it missed most kids with autism. It caught about one in three cases.
How this fits with other research
Shandley et al. (2014) looked at the same urine marker and saw no group difference at all. The clash may come from different labs, different age groups, or how urine was stored.
Older work backs the idea that urine can spot autism. Burack et al. (2004) found a unique urine pattern in 77 % of prepubertal boys with autism. Catania et al. (1982) saw a special peptide pattern in half of autistic kids.
A big 2025 review by Baker et al. (2025) pools all urine-metabolite studies. It says the signal is real but still too shaky for clinic use.
Why it matters
You can add porphyrin testing to your medical work-up if parents want extra biological data. Tell them it is not a yes-or-no test; it is a clue. Use it alongside ADOS, parent reports, and doctor checks. If levels are high, consider further metabolic or environmental screening.
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02At a glance
03Original abstract
Autism (AUT) is a complex neurodevelopmental disorder that, together with Asperger's syndrome and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS), comprises the expanded classification of autistic spectrum disorder (ASD). The heterogeneity of ASD underlies the need to identify biomarkers or clinical features that can be employed to identify meaningful subtypes of ASD, define specific etiologies, and inform intervention and treatment options. Previous studies have shown that disordered porphyrin metabolism, manifested principally as significantly elevated urinary concentrations of pentacarboxyl (penta) and coproporphyrins, is commonly observed among some children with ASD. Here, we extend these observations by specifically evaluating penta and coproporphyrins as biological indicators of ASD among 76 male children comprising 30 with validated AUT, 14 with PDD-NOS, and 32 neurotypical (NT) controls. ASD children (AUT and PDD-NOS) had higher mean urinary penta (P < 0.006) and copro (P < 0.006) concentrations compared with same-aged NT children, each characterized by a number of extreme values. Using Receiver Operating Characteristic curve analysis, we evaluated the sensitivity and specificity of penta, copro, and their combined Z-scores in ASD detection. The penta sensitivity was 30% for AUT and 36% for PDD-NOS, with 94% specificity. The copro sensitivity was 33% and 14%, respectively, with 94% specificity. The combined Z-score measure had 33% and 21% sensitivity for AUT and PDD-NOS, respectively, with 100% specificity. These findings demonstrate that porphyrin measures are strong predictors of both AUT and PDD-NOS, and support the potential clinical utility of urinary porphyrin measures for identifying a subgroup of ASD subjects in whom disordered porphyrin metabolism may be a salient characteristic.
Autism research : official journal of the International Society for Autism Research, 2012 · doi:10.1124/mol.110.069831