A blood test to establish the level of T3 (triiodothyronine) - the active thyroid hormone which regulates metabolism in our cells.
T3 (triiodothyronine) is converted from T4 in our tissues (mainly the liver) by the removal of an atom of iodine. T3 is the active thyroid hormone which regulates metabolism by controlling the rate at which oxygen and calories are converted to energy in our cells. If T4 is low then it is likely that T3 will also be low. In an overactive thyroid T3 is often raised before T4 and returns to normal after T4.
It is not always the case that a low T3 reading signifies a problem with the thyroid gland. Sometimes T3 can be low even when T4 is normal as a result of conversion problems: in times of stress the body will convert T4 to reverse T3 (rT3) an inactive form of T3 in order to conserve energy; at other times mineral deficiencies can cause conversion problems, especially if selenium and zinc are low.
We will send you your T3 finger-prick blood and test sample collection kit which contains everything you need to take your blood and sample in the comfort of your own home. If you are unsure about completing a finger-prick blood sample collection you will have the opportunity to select a clinic-based venous blood sample collection or choose to go our London laboratory during the checkout process.
Your T3 test includes 1st class postage and packaging for you to send your blood and sample directly to our laboratory for analysis. If you live in an area where you cannot rely on the post or you simply want to ensure that your sample arrives at the laboratory the following day, you may wish to send your blood and sample guaranteed next day delivery for extra reassurance.