Urinary Porphyrin Profiles and Trace Element Imbalances in Children with Autism Spectrum Disorders: Insights into Environmental and Metabolic Biomarkers

Porphyrins are intermediates in heme biosynthesis and have been proposed as biomarkers of metabolic dysfunction and environmental exposure in autism spectrum disorder (ASD). This study aimed to evaluate urinary porphyrin fractions and trace element ratios in children with ASD compared to neurotypical controls. Urinary porphyrins were quantified using high-performance liquid chromatography (HPLC), and trace elements were measured via inductively coupled plasma mass spectrometry (ICP-MS) normalized to urinary creatinine. Trace element ratios (e.g., Zn/Cu, Se/Pb) were calculated. Statistical comparisons were made using the Mann-Whitney U-test. Children with ASD showed significantly elevated urinary levels of coproporphyrin (median: 1.94 µg/g creatinine vs. 1.32 in controls; <i>p</i> = 0.02) and pentacarboxyporphyrin (0.86 vs. 0.57; <i>p</i> = 0.01), and reduced hexacarboxyporphyrin (0.12 vs. 0.23; <i>p</i> = 0.03). Lead (Pb) levels were significantly higher in ASD (median: 1.96 µg/g creatinine vs. 0.82; <i>p</i> = 0.004), while mercury (Hg) was not significantly different. Several trace element ratios differed significantly: Zn/Cu (ASD 41.9 vs. controls 49.1; <i>p</i> = 0.021), Se/Pb (12.9 vs. 25.7; <i>p</i> = 0.002), Cu/Se (0.49 vs. 0.38; <i>p</i> = 0.008), and Zn/Pb (19.5 vs. 44.8; <i>p</i> = 0.002). The Hg/Se ratio did not differ significantly.: Children with ASD demonstrate altered porphyrin profiles and trace element imbalances, including increased Pb and disrupted Zn/Cu and Se/Pb ratios, indicating oxidative stress and impaired detoxification. Combined assessment of porphyrins and trace element ratios may provide valuable non-invasive biomarkers for environmental and metabolic disturbances in ASD.