Transient hypothyroidism in a breastfed infant after maternal use of iodoform gauze.

We describe transient hypothyroidism induced in a 2 week-old breastfed infant by maternal use of iodoform gauze for a perirectal abscess. The initial newborn thyroid screen was normal. Low levels of thyroid hormone were discovered during a routine second newborn screen. Thyroid function has since normalized with short-term therapy with thyroxine and after the mother discontinued use of the packing iodoform gauze. This case illustrates the need to avoid iodine-containing products in breastfeeding mothers.