A lack of iodine can cause Hypothyroidism. BUT, if you are diagnosed with Hashimoto Thyroiditis or Graves disease you need to be very careful when implementing an Iodine Supplement. 

It is possible for people with Hashimoto's not to be on thyroid replacement medication. But this does not necessarily depend on the amount of iodine you are consuming or supplementing.  I explain in my video.

Iodine: https://exclusivelyholistic.com/product/iodine/