THE METABOLISM OF IODOTYROSINES. II THE METABOLISM OF MONO- AND DI-IODOTYROSINE II CERTAIN PATIENTS WITH FAMILIAL GOITER*

Abstract

When I131-labeled dl-di-iodotyrosine (T2*) is injected intravenously into patients with treated myxedema (1) or into normal subjects (2), labeled iodine which appears in the urine is almost entirely inorganic iodide. Only a small fraction of the administered T2* escapes deiodination. I131-labeled l-mono-iodotyrosine (T1*) is similarly deiodinated; but in the case of labeled d-mono-iodotyrosine, a large fraction appears unchanged in the urine. After ingestion or injection of I131, very little (3) if any (4, 5) labeled free mono- or di-iodotyrosine appears in the serum. Recently both labeled mono-and di-iodotyrosine were detected in large amounts in the serum of a patient with hypothyroidism and familial goiter (6). One possible explanation for this unusual finding was that degradation of these substances might be defective.