A Case of a Partial Defect of the Iodide Trapping Mechanism¹

Abstract

A case of a partial defect of the iodide trapping mechanism is presented. The patient, a 9-yr-old boy, had a goiter, and a bone and mental age of 5 yr. The thyroidal radioiodine uptake and clearance were decreased and did not increase after TSH stimulation. Although the saliva/plasma ratio of iodide was definitely decreased, the iodide-trapping capacity of the salivary glands was not entirely absent. The thyroid/medium ratio of iodide in slices of thyroid tissue was 1.7. Light and electron microscopic studies were consistent with a functionally hyperactive gland. Biochemical investigation of the thyroid tissue showed a low iodine concentration and a poor iodination of thyroglobulin.