I'm symptomatically hypothyroid but can't tolerate NDT, T3, slow-release T3, and hit a ceiling with T4 at 50 mcg. I've tried the big cofactors such as selenium, iron, hydrocortisone, and am now trying iodine based on Brownstein's protocol. When I increase my T4 dose too much I get worse brain fog and fatigue, and this is even worse if I add T3. My questions: Is it possible to have symptoms that seem exclusive to hypothyroidism (thinning eyebrows, myxedema in upper arms in particular) but are really mitochondrial? I've read in multiple places how the thyroid regulates mitochondria, but does this mean that it is more fundamental than mitochondria? IOW, can mitochondrial dysfunction be "look like" hypothyroidism when it really isn't? How can we separate the two?