Are urinary porphyrins a valid diagnostic biomarker of autism spectrum disorder?
Urinary porphyrin testing does not help diagnose autism or judge its severity.
01Research in Context
What this study did
Shandley et al. (2014) compared urine samples from kids with autism and typical kids.
They measured porphyrin levels to see if the chemical pattern could spot autism or tell how severe it was.
The team used standard lab tests and checked the numbers with statistics.
What they found
Porphyrin levels were the same in both groups.
The test could not tell who had autism and who was typical.
It also failed to match how strong the autism traits were.
How this fits with other research
Two years earlier, Rojahn et al. (2012) saw higher porphyrins in many kids with autism.
That study said the test caught about one-third of cases, so it might help as an extra screen.
Kerrie’s stricter methods found no rise, so the early signal was likely a false lead.
A wider 2025 review by Baker et al. (2025) now lists porphyrins as “not ready” until stronger proof arrives.
Why it matters
You can skip urinary porphyrin tests when you assess for autism.
Stick to gold-standard tools like ADOS and parent interviews.
Save families time, money, and worry by leaving this biomarker out of your report.
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02At a glance
03Original abstract
A fundamental challenge to the timely diagnosis of Autism Spectrum Disorder (ASD) is the reliance on the observation of a set of aberrant behavior. Consequently, the diagnostic process requires that the child reach an age where the behaviors would typically be exhibited. The identification of a reliable biological marker (biomarker) could be of considerable benefit to the diagnostic process. As a diagnostic biomarker, porphyrins present an attractive prospect as previous studies have reported consistent findings of children with ASD showing significant elevations in porphyrin levels in contrast to controls. Furthermore, there is some evidence that ASD severity may be associated with porphyrins, which would be a valuable characteristic of any ASD biomarker. Importantly, for practical use, porphyrins can be tested non-invasively via a sample of urine. The present study sought to investigate whether porphyrin profiles can reliably be used to (a) differentiate ASD cases from healthy controls; and (b) predict ASD severity. The study compared the porphyrin levels of three groups of children aged 2-6 years: Group 1-children diagnosed with ASD (n = 70); Group 2-healthy, normally developing siblings of children diagnosed with ASD (n = 36); and Group 3-healthy, normally developing children with no known blood relative diagnosed with ASD (n = 54). The results of logistic regression analyses failed to find support for the hypotheses that porphyrin levels could be used as a valid tool to detect ASD cases or predict severity.
Autism research : official journal of the International Society for Autism Research, 2014 · doi:10.1002/aur.1385