The common TSH – Thyroid Stimulating Hormone is known as the TFT blood test.
Although this is called the Thyroid Function Test (TFT) it only tests for the one hormone.
This hormone is a secretion from the Pituitary hormone and not your Thyroid.
It is a messenger hormone and its’ release is stimulated further upstream by another hormone from the Hypothalamus called the Thyrotropin Releasing Hormone TRH.
The release of TRH is caused by the lack of hormone being detected in the body.
Once the Thyroid has been stimulated it will excrete from its’ stores of hormone. Mainly T4 and some T3 will be released into the blood stream.
Thyroxine, T4 is a combination of a small protein molecule called an amino acid of Tyrosine molecule with 4 mineral molecules of Iodine.
Once the T4 is released into the blood stream it circulates the body. A molecule of Iodine will be cut off from the T4 by an enzymes called deiodinase. It then becomes the active hormone T3 or changed again by different deiodinase into T2 or RT3 – Reverse T3.
RT3 or Reverse T3, is the mirror image of Active T3 and it is this hormone that will block the activity of the active T3. RT3 is commonly elevated in times of stress or too much medicated Thyroxine.
There are three Thyroid antibodies to test for:
Thyroperoxidase Antibody, TPOab
Thyroperoxidase is the enzyme that takes hydrogen peroxide that is made in the Thyroid cell and breaks it apart into Oxygen and Hydrogen. The Oxygen is then used to turn the Iodide into Iodine before it attached to the Thyroglobulin prior to the formation of T4. As you can imagine, if there are antibodies involved in this process with Hydrogen Peroxide involved there will be excessive inflammation and toxic damage. That is why TPOab is considered most aggressive and damaging of the Thyroid gland.
ThyroGlobulin Antibody, TGab
The Thyroglobulin is a large protein molecule that is made within the Thyroid cell and becomes the backbone on which the newly made T4 and some T3 are attached. This protein molecule takes the hormones from the central colloid reservoir back to the external cell wall where the Thyroglobulin is dissolved and the T4 and T3 are released and excreted into the blood stream. The antibodies will work against this protein molecule.
Thyroid Receptor Antibodies, TRabs
The TSH attaches itself to the Thyroid Receptors on the external cell wall. This in turn stimulates the production of the Thyroid hormones. If these receptors are over stimulated then the production of Thyroid hormone increases such in the case of Graves disease where there are too much Thyroid hormone sent around the body.