Free triiodothyronine is a hormone produced by the thyroid, a gland located in the neck. Its abnormal level leads to dysfunctions in the regulation of the body.

Triiodothyronine is a hormone secreted by the thyroid gland. The latter is located at the level of the neck, presents an aspect of “butterfly” or “H” with its two lobes. The thyroid plays a major role in our body. It is indeed this which will produce two hormones, Triiodothyronine, which is nicknamed T3, and thyroxine (known as “T4”). These two hormones will circulate in the body’s blood network, in order to provide information to the various organs (heart, lungs, brain, etc.). They therefore have a role of “messengers”, in the sense that it is through them that the body transmits information in order to regulate its various functions. We can also see it as the fuel of the great engine that is our body: it is what decides in a way the speed of operation of our various organs, and the way in which each one must use its resources (whether they are proteins , lipids or sugars).

As for “Free Triiodothyronine”, or “FT3” (Free T3), this is a measurement use, because it is its measurable variant in the blood (we also sometimes speak of “total triiodothyronine “). Because “bound” T3 is directly attached to proteins, it cannot be measured.

Both T3 and T4 are produced by the activation of thyroperoxidase (TPO) and thyroid stimulating hormones (TSH) hormones in the thyroid gland.

Normally, thyroid hormones are at levels that allow them to regulate the body.

• The normal level of T3: In the body, T3 has a normal level of 0.6 to 2.2 umol / L.
• Normal levels of T3-FT3: For free T3, or FT3, the normal dosage is between 2 to 6 ng / L, or 3 to 9 pmol / L.
• The normal level of free T4: the average level of free T4 in adults is 9 to 17 ng / L, or 12 to 22 pmol / L.
• The normal level of ultra-sensitive TSH: the average level of ultra-sensitive TSH is 0.4 to 4 mIU / L.

The measurements of FT3 are generally carried out in case of suspicion of hypothyroidism and hyperthyroidism. Indeed, it is an effective tool to identify a dysfunction of our thyroid gland, which is often inaccessible to measurements. The blood test is carried out by simple sampling, then laboratory analysis with results in the days that follow. Your doctor will then be able to make a diagnosis, based on too high or too low a level of hormones in the blood.

Hypothyroidism

This is too low a hormonal level. It can be caused by different disorders. First of all, a failure of the thyroid gland, which will secrete too low a level of hormones. Other times, it is a poor supply of minerals in the body that causes this hormonal dose to be low.

Normally, when the level of T3 or T4 is too low, the pituitary gland will stimulate the production of TSH (thyroid stimulating hormone) in order to produce more.

The results

It is difficult to accurately describe the consequences of hypothyroidism. Indeed, the low hormonal intake will have very different consequences depending on the individuals and organs that lack it.

In its most severe forms, hypothyroidism can lead to myxedema, which is characterized by a puffy face, a yellow complexion, and dry, thick skin. Then, if left unchecked, the disorder can lead to myxedema coma.

Hyperthyroidism

Unlike hypothyroidism, hyperthyroidism refers to an abnormally high production of hormones secreted by the thyroid gland. There are different causes:

• Graves’ disease: an autoimmune disease in which the antibodies stimulate the thyroid;
• Thyroiditis: inflammation of the thyroid;
• Thyroid nodules: nodules formed in the thyroid gland.

The results

The consequences of hyperthyroidism will be, like its hypothyroid addiction, varied in nature. Overall, given the “motor” role of the thyroid, there is an amplification of the metabolism, and therefore too much energy expenditure in relation to our needs. This can lead to osteoporosis, linked to too much calcium absorption by the bones of the body, as well as an excessively high heart rate (arrhythmia). In the long term, it can lead to a thyrotoxic crisis, with a significant risk of heart failure and again coma.