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Goitrogens are substances that suppress the function of the thyroid gland by interfering with iodine uptake, which can, as a result, cause an enlargement of the thyroid, i.e., a goiter.
Goitrogenic drugs and chemicals
Chemicals that have been shown to have goitrogenic effects include:
- Sulfadimethoxine, propylthiouracil, potassium perchlorate, and iopanoic acid.
- Some oxazolidines such as goitrin.
- Ions such as thiocyanate and perchlorate decrease iodide uptake by competitive inhibition and, as a consequence of reduced thyroxine and triiodothyronine secretion by the gland, cause, at low doses, an increased release of thyrotropin (by reduced negative feedback), which then stimulates the gland.
- Amiodarone inhibits peripheral conversion of thyroxine to triiodothyronine; also interferes with thyroid hormone action.
- Lithium inhibits thyroid hormone release.
- Phenobarbitone, phenytoin, carbamazepine, rifampin induce metabolic degradation of triiodothyronine (T3) and thyroxine (T4).