DEFECTIVE IODINATION OF TYROSINE A CAUSE OF NODULAR GOITER?*

Abstract

Twenty patients with colloid nodular goiter, 7 patients with Hashimoto''s struma, and 15 patients without thyroid disease (all non-deaf) were tested with radioactive iodine and potassium thiocyanate for a thyroidal defect in iodination of tyrosine. In the cases of colloid nodular goiter with a family history of goiter there was a higher incidence and more severe degree of defective iodination of tyrosine than in the cases of colloid nodular goiter without a family history of goiter. Defective iodination of tyrosine was demonstrated in 1 sibling with proved colloid nodular goiter and in 1 with Hashimoto''s struma. Iodination of tyrosine was impaired in 1 patient with her fourth recurrence of colloid nodular goiter. These data suggest that defective iodination of tyrosine is not uncommon in euthyroid non-deaf subjects with colloid nodular goiter, and may occur on a familial basis.