Effect of Cadmium on Thyroid Hormone Metabolism
Monodeiodination is a major pathway of T4 metabolism in the rat as well as in man. The active thyroid hormone, T3, is produced by outer ring deiodination of T4. Thiol agents such as dithiothreitol (DTT), mercaptoethanol, and reduced gluthathione are potent stimulators of this reaction (1). The sulfhydryl-oxidizing agent, diamide, on the other hand, is a potent inhibitor. Heavy metals bind firmly to free sulfur groups and inhibit activities of a large number of enzymes having functional sulfhydryl groups (2). The inhibitory effect of mercury on the conversion of T4 to T3 in vitro has been reported (1,3). In the present paper we describe the effect of cadmium on the hepatic conversion of T4 to T3 in the rat. Furthermore, we have measured serum thyroid hormone concentrations in subjects living in a cadmium polluted area for a long time.
KeywordsThyroid Hormone Cadmium Concentration Active Thyroid Hormone Thyroid Hormone Metabolism Serum Thyroid Hormone Concentration
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