Thyroid Function of Infants Breastfed by Mothers with Graves Disease Treated with Inorganic Iodine: A Study of 100 Cases

Abstract Context We previously reported that inorganic iodine therapy in lactating women with Graves disease (GD) did not affect the thyroid function in 25 of 26 infants despite their exposure to excess iodine via breast milk. Objective To further assess thyroid function in infants nursed by mothers with GD treated with inorganic iodine. Design Case series Setting Tajiri Thyroid Clinic, Japan Participants One hundred infants of lactating mothers with GD treated with potassium iodide (KI) for thyrotoxicosis Main Outcome Measures Infant blood thyrotropin (TSH) and free thyroxine (FT4) levels were measured by the filter paper method. Subclinical hypothyroidism was defined as TSH ≥10 μIU/mL and ≥5 μIU/mL in infants aged