MustardSeed -
All good responses so far. I would definitely do a 24-hr saliva test for adrenal and neurotransmitter function as well as do some more specific thyroid levels for T3, T4 and reverse T3 and T4.
TSH - is a measurement of the signal from your pituitary gland that tells your thyroid to produce T3 and T4.
T4 - Your TSH might indicate that your pituitary is sending the right signal to your thyroid, but without measuring how much T4 (or thyroxine) is being produced, you have no way of knowing whether or not the thyroid is receiving the signal and responding like it should, by producing T4.
T3 - results when T4 converts to T3 (a process known as monodeiodination, when T4 loses an atom and becomes triiodothyronine, the active thyroid hormone). In hypothyroid conditions, T3 can be low. The majority of thyroid hormones produced by the thyroid are T4, however, T3 is the most active useable form of thyroid hormone that can be used in the body’s cells. The conversion of T4 to T3 is a critical process and necessary before the body can use it and these levels need to be measured.
Total T4 and Total T3 and Free T4 and Free T3 - There is also a difference between Total T4 and Total T3 versus Free T4 and Free T3. Thyroid hormones are fat soluble and in order for them to travel through the vessels, they need to be bound to protein. When they reach the cells the protein needs to be cleaved off because only the unbound “free” hormones can actually enter the cells and perform their necessary functions. Therefore, Free T4 and Free T3 levels are also important measurements.
RT3 - In some cases, the body conserves energy by converting the T4 instead into reverse T3 (RT3), an inactive form of T3 that is incapable of delivering oxygen and energy to the cells as T3 does. Elevated RT3 levels can be triggered by ongoing chronic physical/emotional stress, adrenal fatigue, low ferritin (iron) levels, acute illness/injury, chronic disease, etc.
A full thyroid panel for hypothyroidism or any condition that might cause heart-related symptoms should also include Thyroid Peroxidase and Thyroglobulin as well as TSH, Free T4, Free T3 and Reverse T3. These tests are most accurate in context with basel body temperature, physical exam and medical history.
According to Kent Holtorf, MD, a Reverse T3 level above 150 -- or a Free T3/Reverse T3 ratio that exceeds .2 [when the Free T3 is measured in picograms per milliliter (pg/mL)] -- may indicate hypothyroidism.
Says Dr. Holtorf:
A high reverse T3 demonstrates that there is either an inhibition of reverse T3 uptake into the cell and/or there is increased T4 to reverse T3 formation. …reverse T3 is an excellent marker for reduced cellular T4 and T3 levels not detected by TSH or serum T4 and T3 levels. …high or high normal RT3 is not only an indicator of tissue hypothyroidism but also that T4 only replacement would not be considered optimal in such cases and would be expected to have inadequate or sub-optimal results.
Most of the above is summarized from the following article - has a lot more detail:
/www.verywell.com/the-role-of-reverse-t3-testing-in-thyroid-treatment-3233184-p
(Edited to clarify info)
Post Edited (Pirouette) : 7/12/2016 11:16:40 AM (GMT-6)