It can be difficult finding a doctor who will work with you on treating the thyroid for optimal health and function as opposed to at least barely escaping fairly severe disease state.
(In other words, many doctors feel that values need merely to be kept within the “reference range,” even though much of that range is quite bad.)
The site has a recent article on thyroid: https://www.T-Nation.com/diet-fat-loss/what-you-dont-know-about-your-thyroid
Some brief excerpts of particular relevance:
Range of Thyroid Levels Indicating Proper Signaling
Free T3: Middle to the upper part of your test’s normal range
Free T4: Middle to the upper part of your test’s normal range
TSH: Preferably no more than 2, even more preferably 1.5 or less
Doctors often omit testing for free T3, but the value really is needed for good diagnosis. Total T3 can be deceptive, as most of the total is inactive.
You don’t need total T3 or total T4. If the free values are fine then the total values don’t matter. Likewise for T3 Uptake and Free Thyroxine Index: you don’t need them.
If free T3 is good, then TSH at the lower end is fine, or even beneficial. (I’m assuming thyroid medication isn’t being taken.)
Overly high TSH generally shows poor thyroid function, requiring abnormally high stimulation to compensate or partially compensate.
High TSH has adverse effects of its own on metabolism, working towards causing metabolic disorder.
If test values aren’t quite so good as these, there’s no sharp transition between “good” and “bad.” It becomes a very slowly sliding scale, with different meanings in different situations. If your results are greatly different from the above and if actions can improve those values, they’ll be worth taking.[/quote]
And on how much iodine intake is needed:
About 12% of Americans are seriously deficient in iodide as measured by urinary analysis. Many more are moderately deficient or sub-optimal. So while diet alone can provide good iodide intake, very often it doesn’t. It’s worth giving your food choices and iodized salt intake a quick lookover.
If most of your food is homemade and salted with a medium-to-heavy hand with iodized salt, you should have good iodine intake already. If not, then you should increase it.
How much iodized salt is needed, if it’s your principal source of iodide? When iodized salt is at full potency, it takes about 2 grams or about half a teaspoon of iodized salt (about 936 mg sodium) to meet your rock-bottom minimum for iodide consumption.
Generally, fast foods, processed foods, and restaurants don’t use iodized salt. If a label reads merely “salt” instead of “iodized salt,” it’s not iodized. And “sea salt” contains little iodide.
As a way of looking at how iodine-rich some foods are, you could meet a 150 mcg/day requirement by consuming any one of these in about the following amounts:
2.5 cups of milk, yogurt, or cottage cheese per day
2.5 baked potatoes with skin
13 ounces of shrimp or of “average” saltwater fish
13 ounces of turkey
Beef, chicken, pork, rice, most wheat products, fruits, and vegetables are too low in iodine to be major sources. Seaweed or kelp are extremely rich but aren’t common foods in America.
Also, whey protein concentrate and micellar casein are pretty rich in iodide. It takes only about 80 grams of these proteins, give or take, to provide 150 mcg iodine.
So if your diet has several of the above things or a lot of even one of them, you won’t need iodized salt or a supplement. But if your diet is strong on things like beef, chicken, vegetables, pasta, and fruits and weak on the above, then iodized salt or a supplement will probably be beneficial.[/quote]
So briefly, if it appears your choice of foods may not be supplying sufficient iodine and you do not take an iodide-containing supplement or use much iodized salt, you’re likely iodine deficient.
Vitamin D deficiency can be another reason for low thyroid activity, and also causes its own problems for fat loss.
If your TSH is above 2, that would be a sign of having impaired thyroid, even if a given doctor would consider that “subclinical.”
If your free T3 (different from total) isn’t at least about midrange, thyroid function could be impaired. If it’s well below midrange, it certainly is.