Nontoxic Goiter

NONTOXIC GOITER

Nontoxic goiter is a syndrome of thyroid enlargement without excessive thyroid hormone production. Enlargement of the thyroid gland is often due to TSH stimulation from inadequate thyroid hormone synthesis. The most common cause of nontoxic goiter worldwide is iodide deficiency, but in the USA, it is Hashimoto’s thyroiditis. Other causes include germ-line or acquired mutations in genes involved in hormone synthesis, dietary goitrogens, and neoplasms .

Goiter due to iodide deficiency is best managed by prophylactic administration of iodide. The optimal daily iodide intake is 150–200 mcg. Iodized salt and iodate used as preservatives in flour and bread are excellent sources of iodine in the diet. In areas where it is difficult to introduce iodized salt or iodate preservatives, a solu-tion of iodized poppy-seed oil has been administered intramuscu-larly to provide a long-term source of inorganic iodine.

Goiter due to ingestion of goitrogens in the diet is managed by elimination of the goitrogen or by adding sufficient thyroxineto shut off TSH stimulation. Similarly, in Hashimoto’s thyroidi-tis and dyshormonogenesis, adequate thyroxine therapy— 150–200 mcg/d orally—will suppress pituitary TSH and result in slow regression of the goiter as well as correction of hypothy-roidism.