Thought this was interesting. High doses of iodine do not cause autoimmune or hyperthyroid.
Conclusion: Iodine supplementation may not induce an increase in hyperthyroidism in a previously mildly iodine-deficient population. Chronic iodine excess does not apparently increase the risk of autoimmune hyperthyroidism, suggesting that excessive iodine intake may not be an environmental factor involved in the occurrence of autoimmune hyperthyroidism.
http://www.eje-online.org/content/156/4/403.full
That person has cancer.
Most likely, they have a hot nodule and were eating iodine foods that could be high in bromides.
Iodine doesn't cause heart palpitations, but excess thyroid hormone does.