ABSTRACT
Iodine enters the thyroid follicular cells as inorganic iodide and is transformed through a series of metabolic steps into thyroxine and triiodothyronine. The first step in the utilization of iodine by the thyroid gland is iodide transport as the thyroid extracts iodide from plasma and concentrates it in the interior of the cells and in the colloid. Goiter may be diffuse or nodular and in a few patients it has been small or absent and is often recognized well after the hypothyroidism is observed. By contrast, hypothyroidism may appear late, and the other clinical features, including mental retardation, have varied considerably. An analysis of the changes of hormone level measured during iodide therapy with increasing graded doses of hydriodic acid was reported by M. C. Gershengorn et al. in a patient with the iodide transport defect.
