'Travelers' thyrotoxicosis'. Transitory thyrotoxicosis induced by iodinated preparations for water purification.

Two young adults presented with thyrotoxicosis after increased iodide ingestion in the course of backpacking trips to Central and South America, during which each of them used an iodinated preparation for water purification. In both cases, serologic tests were positive for antithyroid peroxidase antibodies, and one had a family history of immune thyroid disease. We suggest that in these two cases the condition was a variant of iodide-induced thyrotoxicosis, reflecting an inadequate response to iodide excess in association with a presumed preexisting asymptomatic immune thyroid disease. This observation adds a new consideration for travelers' consultation.