The biological action of substances related to thyroxine. 7. The metabolism of butyl 4-hydroxy-3:5-diiodobenzoate

Abstract

A study was made of substances excreted in urine after admn. of butyl 4-hydroxy-3,5-diiodobenzoate (BHDB) to man, rabbits and rats. In the urine of 7 patients with thyro-toxicosis, 2 patients with myxedema under treatment with thyroxine, and 1 normal volunteer the principal excretory products found were 4-hydroxy-3,5-diiodobenzoic acid and its methyl ether. These 2 acids accounted for 90% or more of total urinary I. Less than 2% of the urinary I consisted of iodide. Excretion of the methoxy acid appeared to be greater in patients with thyrotoxicosis than in other subjects studied. Implications of this observation in relation to processes of biological methylation are discussed. In rabbits and rats treated with BHDB, only the hydroxy acid was isolated from the urine.