A group of Italian researchers is recommending routine thyroid-function screening for women during early pregnancy, because they believe attention deficit and hyperactivity disorder (ADHD) in children may be associated with an iodine deficiency in mothers.

The thyroid is a gland that helps regulate body growth and metabolism. The gland requires iodine to form thyroid hormone, a substance that is necessary to keep the body functioning normally. The condition in which levels of iodine in the thyroid gland are too low is called hypothyroxinemia.

Based on a study that lasted almost 10 years, the Italian researchers believe that hypothyroxinemia in mothers during pregnancy may increase the risk of ADHD in their children.

The researchers followed the children of 16 women in an area of the Italian island Sicily where iodine deficiency is common, comparing them to children in a region where iodine is sufficient.

ADHD was diagnosed in 11 of the 16 children from the iodine-deficient area, but in none of the children in the comparison group.

Dr. Francesco Vermiglio, who led the study, told Reuters Health that he believes the ADHD and a related reduction in IQ seen in the study resulted from hypothyroxinemia in the children’s mothers during the first half of pregnancy. Seven of the 11 ADHD children were born to mothers who became hypothyroxinemic during early pregnancy.

Vermiglio and his colleagues at the University of Messina in Italy published the findings of their study in the December issue of the Journal of Clinical Endocrinology and Metabolism.

They note in their report that hypothyroxinemia in pregnant women can occur even in places where iodine intake is adequate, and that they therefore recommend routine thyroid screening and monitoring for all pregnant women.

SOURCE: Journal of Clinical Endocrinology, December 2004.