This is one of the main metabolic disorders we treat at the clinic. To understand the thyroid better, Click Here to be transferred to an article that explains all about thyroid metabolism. Our typical patient comes in and feels they are not taking enough levothyroxine (Synthroid). We first do a Thyroid Panel which rules out (or in) Hashimotos Disease or autoimmune Thyroiditis (a cousin of Rheumatoid Arthritis, only in this case the body is attacking the thyroid and not the joints). We then check T4 and T3 (the two thyroid hormones) to see what the levels are. The great mistake physicians make is prescribing T4 only (that is what levothyroxine is) because some people either have a low level or a decrease with aging of an important enzyme 5deiodinase which has one simple function in the body. It removes an Iodine from T4 (which has 4 iodine atoms hence the reason we call it T4) converting it to T3 (which has 3 iodine atoms). T3 is the more active hormone and these non-converters are fatigued but their TSH and Free T4 levels are normal. We thoroughly evaluate the thyroid and will switch to natural thyroid (which has a T4/T3 ratio of 4/1) or will simply add time release T3.