your post is an example of how treating the digestive system improves thyroid function, thank you VERY MUCH:) That being said, the causes of thyroid problems are numerous, dysbiosis, hormonal issues, stress, heavy use of antibiotics, iodine deficiency(and it's myriad causes), heavy metals, etc. Include in that list a genetic predisposition towards hypothyroid...

The fact is that if one throws iodine or thyroid glandulars at a problem without treating the whole system, long-term success is not likely, IMO.

That being said, in my opinion there are times when supplemental glandulars are desirable. There are those whose health is so compromised that they need the "jump-start" that glandulars can give. I would imagine that it would be quite difficult to tend to cleansing and optimal diet when one is sleeping 12 hours a day and sleepwalking through the waking hours, for instance. 

The Dr. Mark Starr book is entirely based on Dr. Broda Barnes' book, "Hypothyroidism, the Unsuspected Illness."

One extremely important factor not emphasized enough in both books is the impact that digestive health(or lack thereof) has on the workings of the thyroid gland. There is no doubt that typical western diet leaves much to be desired, with heavy usage of processed foods, high simple carbs, heavy usage of polyunsaturated vegetable oils and heavy meat consumption. 

I've posted on this before, I'll reiterate here. Much of the genetic change that Dr. Mark Starr attributes to poor thyroid function are also exemplary of poor nutrition due to western diet.

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http://www.jimotisdc.com/colon.html

Intestines and Thyroid Function

The intestines activate up to a third of thyroid hormone into its active form. Food allergies and dysbiosis interfere with this process, and can lead to thyroid problems. Read Thyroid Health for more information.

tp://www.jimotisdc.com/thyroid.html

Most problems with the thyroid system are not with the thyroid gland itself, but with other parts of the system. Conventional thyroid replacement therapy (with synthetic thyroxin) is helpful to a degree, but it usually misses the underlying dysfunction and it often has undesirable side effects. 

It is important to manage your adrenal stress response.  Stress damages the thyroid system in three ways. High cortisol, the stress hormone, blocks the release of TSH, it blocks the conversion thyroid hormone into its active form, and it blocks thyroid receptors so that cells don’t respond to the thyroid hormone. Read Stress and Your Hormones for details about how to deal with adrenal stress reactions.  

It is important to make sure that your colon is working well. Intestinal dysbiosis, a condition in which there are unhealthy bacteria and fungus in the colon, hampers the thyroid system by reducing the conversion of thyroid hormone into its active form. It also sets the stage for autoimmune attack on the thyroid gland. Read Your Colon and Your Health for more information. 

Nutritional support is often helpful. Many people with autoimmune disease, including 90% of people with Hashimoto’s Thryroiditis (a common thyroid autoimmune disease) have difficulty converting vitamin D into its active form. Supplementation with vitamin D3 is often helpful.

Zinc and selenium are necessary for conversion of T4 into T3. If zinc and selenium levels are low, it is important to determine why they are low. Sometimes the body is using its reserves of zinc and selenium to deal with infections or other health conditions.