I can guarantee you 100% that you are deficient in Iodine if you are hypothyroid!!!
Not necessarily. There are numerous causes of hypothyroidism and many do not involve a lack of iodine. Elevated estrogen for example or chronic stress will both suppress thyroid function and do not involve an iodine deficiency.
chronic stress? wow
Chronic stress inhibits T4 to T3 conversion.
Interestingly, temporary stress actually raises thyroid hormone levels temporarily, which is one of the reasons lab thyroid tests often do not catch cases of hypothyroidism.