"T1, T2, T3 and T4 are released into the blood vessels so it can be used by the rest body. T4 is converted elsewhere to T3 as needed. This conversion requires selenium."
Now, look at how selenium levels are typically low inmost people, just like with potassium. Selenium is almost always low in people who have cancer, easy to search and verify. So, when these same people who are low in selenium also have low T3, it is not because of iodine, just low selenium