I have not read about iodine issues with sodium chloride.

Thyroid hormones are in the blood, but have to enter the cell to become active in the cell, cortisol is necessary in the equation. For me even getting a filling makes my cortisol levels decrease and my temp will drop down to 95 overnight. Low cortisol levels can be seen in variability in your first in the morning temps.

There isn't enough B12 in the b vitamins and it's absorbed under the tongue.

You don't want to have normal ferritin values, you want optimal for thyroid problems. I only had this problem in perimenopause when my periods became excessive.

Although all this stuff can help optimize, I found it's nothing without thyroid medication.