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477 Molybdenum Toxicity: Toxic Leukoencephalopathy as a Cause of Autism.
  1. G. Ordog.
  1. Henry Mayo Hospital, Valencia, CA


Study A case series of children presenting to a medical toxicology department for evaluation of previously diagnosed autism. Each patient had an evaluation for potential heavy metal toxicity as the etiology. The past medical records were reviewed. A history and physical examination were done. An initial heavy metal screening followed by a chelation challenge test (24-hour urine collected after 50 mg/kg of succimer [DMSA] orally administered) was done for each. Heavy metal testing was done by mass spectroscopy. Other neurological etiologies were ruled out.

Results Study period: 2002 to 2005. Six patients met the criteria. Ages ranged from 2 to 5 years. Each had the development of symptoms temporally associated with the administration of injectables, including vaccination and parenteral antibiotics (ceftriaxone). All were nonverbal and developmentally delayed by neurocognitive testing, and other etiologies were ruled out by pediatric neurologist evaluation. Screening heavy metal panels confirmed borderline levels of various metals including molybdenum and mercury. Chelation challenge test confirmed markedly elevated molybdenum between 2 and 30 times the upper limit of normal (based upon industrial exposure standards). The chelation challenge test was also positive clinically in each case. Two of six patients spoke their first words the day of the initial dose of DMSA. One of six, who had previously been aphonic, started singing complete tunes the day after the first DMSA dose. Treatment was continued for 18 days. Four of the youngest children (ages 2 to 4) were essentially cured and later “delisted” as autistic. The older children, aged 5, had marked clinical improvement but continued to have residual developmental delays after the course of therapy.

Conclusions Heavy metal toxicity, specifically molybdenum toxicity, appears to be a cause of some cases of autism. This is consistent with toxic leukoencephalopathy caused by heavy metal toxicity. The chelation challenge test with elevated 24-hour urinary molybdenum and clinical improvement with the DMSA chelation were the major diagnostic criteria of this illness. The younger the therapy was initiated, the more successful the results, preferably between ages 2 and 4 for maximum improvement. The source of the molybdenum was not determined but may be associated with the use of injectable vaccines and antibiotics. There was a temporal relationship between the development of symptoms and the administration of injectables. Injectables should be analyzed for their content of heavy metals, including molybdenum. Further study is needed for other toxicological causes of autism.

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