Jod-Basedow phenomenon

The Jod-Basedow effect (also Jod-Basedow syndrome and Jod-Basedow phenomenon) is hyperthyroidism following administration of iodine or iodide, either as a dietary supplement or as contrast medium.

This phenomenon is thus iodine-induced hyperthyroidism, typically presenting in a patient with endemic goiter (due to iodine deficiency), who relocate to an iodine-abundant geographical area. People who have Graves disease, toxic multinodular goiter, or various types of thyroid adenoma are also at risk of Jod-Basedow effect when they ingest extra iodine. The Jod-Basedow effect also been seen as a side effect of administration of the iodine-containing contrast agents, or amiodarone, an antiarrhythmic drug.

The Jod-Basedow effect does not occur in persons with normal thyroid glands who ingest extra iodine in any form.

The Jod-Basedow effect is named for the German word for iodine, "Jod" (all nouns are capitalized in German), plus the name of Karl Adolph von Basedow, a German physician who first described the effect.

The Jod-Basedow effect typically occurs with comparatively small increases in iodine intake, in people who have thyroid abnormalities that cause the gland to function without the control of the pituitary (i.e., a thyroid gland that is not normally suppressed by thyroid hormone driven loss of TSH secretion from the pituitary). In some ways the Jod-Basedow phenomenon is the opposite of the Wolff-Chaikoff effect, which refers to the short period of thyroid-hormone suppression which happens in normal persons and in persons with thyroid disease, when comparatively large quantities of iodine or iodide are ingested.

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