The causes of autism spectrum disorder are not fully understood, but there is a possible link to toxic trace elements (such as mercury, arsenic, lead, and cadmium), which may be present in elevated concentrations and cause neurotoxic effects and developmental delays in children. At the same time, deficiencies of essential trace elements (such as copper, zinc, cobalt, and selenium) in children with autism spectrum disorder can impair proper development and function of the nervous system. To investigate this further, a study was conducted involving 149 children, including 94 with a diagnosis of autism spectrum disorder and 55 of their siblings who served as the control group. Urine samples were collected and analyzed using mass spectrometry, specifically inductively coupled plasma mass spectrometry. We expressed the concentrations of trace elements as the ratio between the element concentration and creatinine concentration in the same urine sample, which allowed for more comparable results across different urine samples. The study found that the median concentrations of most trace elements in urine do not statistically differ between the group of subjects with autism spectrum disorder and the control group. Barium (34,2 %) and calcium (40,9 %) concentrations were significantly lower in the group of children with autism spectrum disorder compared to the control group. The median concentrations of barium and calcium in urine samples significantly differed between the two groups (p < 0.05; |^| > 1.96). There was a statistically significant linear relationship between barium and calcium (r = 0.367; p = 0.000) in urine samples. The median concentrations in urine were noticeably higher for tin (19.9 %), arsenic (16.4 %), and lead (13.9 %) in the group of children with autism spectrum disorder. While concentrations of manganese (17.7 %), cadmium (11.0 %) and cobalt (8.2 %) were lower. There were no significant differences in mercury, selenium, copper and zinc concentrations in urine between the two groups. The mean values of the ratio of zinc to copper in the urine of the children were lower in the group of children with autism spectrum disorder (42:1) than in the control group (46:1). We also included the results of the Childhood Autism Rating Scale questionnaires, which assesses the severity of autistic symptoms. Trace element concentrations of lead, arsenic, and aluminium increased with increasing scores on the Childhood Autism Rating Scale, while calcium concentrations decreased significantly with increasing scores. The results of the study suggests that there is some relationship between toxic and essential trace elements and developmental delays in children with autism spectrum disorder.
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