Evaluation of Iodine Deficiency in Children with Attention Deficit/Hyperactivity Disorder

Objective: To investigate the incidence of iodine deficiency (ID) and its effects on mental function in children referred to the Dr. Sami Ulus Maternity and Children’s Training and Research Hospital with a prospective diagnosis of attention deficit/hyperactivity disorder (ADHD).
Methods: The study was conducted on 89 children referred in the period from September 2009 to June 2010 with a diagnosis of ADHD. A questionnaire was given to all parents. Conners’ rating scales were applied to the parents (CPRS) and teachers (CTRS), and revised Wechsler intelligence scale for children (WISC-R) to the children. Serum thyroid-stimulating hormone, free triiodothyronine and free thyroxine, thyroglobulin, anti-thyroid peroxidase, anti-thyroglobulin, and urinary iodine levels were measured in all children.
Results: Median age was 9.41±1.95 years, and 83.1% of subjects were male. The mean urinary iodine level of the children was 92.56±22.25 µg/L. ID was detected in 71.9% of subjects and all were mild ID. There was no significant relationship between urinary iodine levels with WISC-R subtest scores and CPRS. However, a significant association was found between urinary iodine levels and hyperactivity section of CTRS (p<0.05). Likewise, a significant relationship was found between learning disorder/mental retardation diagnosis and freedom subtest of WISC-R (p<0.05).
Conclusion: This study highlights the effects of ID on comprehension, perception, attention, and learning. However, the results need to be supported by new randomized controlled trials.