Elevated Serum Protein-Bound Iodine Values with Dietary Iodine Deficiency

Study of the thyroid function of mildly mentally retarded children in one training school in Michigan, and of deaf children in another training school, showed the former group to be iodine-deficient. Fiftythree children aged 8 to 16 years exposed to this dietary iodine deficiency for an average period of one year differed from the comparable group of 50 children without iodine deficiency only in a twofold elevation of the two-hour thyroidal uptake of I131. A representative group of 17 subjects from 140 residing in the iodine-deficient institution for an average period of ten years, however, differed further in that they had abnormally elevated serum PBI levels (average, 8.8 μg per 100 ml) and PBI-BEI differences (average, 2.9 μg per 100 ml). All subjects were euthyroid. An increased incidence of goiter was also found in the group of 140 subjects exposed to iodine deficiency for a longer period of time. The nature of the material in serum accounting for this increased PBI-BEI difference was not established with certainty, but diiodotyrosine may have been an important component.