Signs of iodine deficiency include elevated thyroid stimulating hormone (TSH) and reverse T3 hormone, with normal or low-normal levels of T4 and/or T3.

Most healthcare professionals know little about reverse T3 testing. I was not taught about it in medical school and I doubt it is being taught today.

Conventional medicine considers reverse T3 an inactive form of thyroid hormone. Some laboratories won’t even test for it because they don’t think it provides any useful information. I strongly disagree.

It’s impossible to fully evaluate thyroid function without looking at reverse T3 level. Elevations are common in those with iodine deficiency.

Supplementing with iodine has been very successful for reducing reverse T3 levels.

Keep in mind that there can be other reasons for elevated reverse T3 that are not related to iodine deficiency, including toxic liver due to heavy metals such as mercury, lead, cadmium, arsenic, and nickel.

In those cases, detoxification of the liver can lower reverse T3 levels.