Obese children risk thyroid damage

WASHINGTON (Reuters) - Obese children may be damaging their thyroids, creating a vicious cycle of metabolism and overweight, Italian researchers reported on Wednesday.

Obesity may cause inflammation that damages the thyroid, which secretes hormones to regulate metabolism and other important functions, Dr. Giorgio Radetti of the Regional Hospital of Bolzano in Italy and colleagues said.

They evaluated 186 overweight and obese children for about three years, testing thyroid hormone levels and thyroid antibodies and imaging the thyroid gland using ultrasound.

"Our study shows that alterations in thyroid function and structure are common in obese children and we may have uncovered the link," Radetti said in a statement.

"We found an association between body mass index and thyroid hormone levels which suggests that fat excess may have a role in thyroid tissue modification."

Writing in the Journal of Clinical Endocrinology & Metabolism, they said 73 of the children had inflamed-looking thyroids, but apparently not a condition called Hashimoto's thyroiditis, an autoimmune disease in which T-cells mistakenly attack the thyroid.

But the children lacked antibodies that are also involved in the disease.

"The ultrasound findings are a bit mysterious," Radetti said. "However, the findings do suggest the existence of a low-grade inflammation state, which has been known to characterize obesity."

More study is needed to show whether losing weight would normalize the thyroid and return the children to health, he said.

Low thyroid function can be linked to weight gain, although stimulating the thyroid does not automatically cause weight loss. Losing weight, however, has been shown to restore thyroid function in some cases.

(Reporting by Maggie Fox, editing by Will Dunham)