T3 - thyroid hormone: what is responsible, the norm and the deviations from the norm

Many know the main function of the thyroid gland, and the hormones it produces are extremely necessary for the normal functioning of the body. The hormone T3 (triiodothyronine) is one of them, and the figure "three" in its definition is explained by the content in each molecule of that very number of iodine atoms. It is formed as a result of the dissolution of another hormone of this gland - T4, when one iodine atom is split off from it. Being inactive, transformed into triiodothyronine T4 becomes excessively active. So what kind of hormone is it and why does it respond? Let's try to figure this out.

How important is triiodothyronine?

T3 is a hormone that controls the energy metabolism in the human body, it promotes the decay of energy and sends it to where it is needed. Thanks to his work, a person's nerve conduction increases. Also important is the hormone for bone tissue and cardiac system, promotes the activation of metabolic processes in them.

What is T3 free and common?

The gland cells are able to produce the required amount of triiodothyronine already with three iodine atoms. Penetrating into the bloodstream, this hormone binds to the molecules of transport proteins and is transported to the tissues that need its work. However, a small amount of triiodothyronine, not associated with protein molecules, remains in the blood. This hormone T3 is free.

The remaining free hormone T3 in combination with the one that is associated with proteins is called generic. It is its number is considered indicative in determining the pathology of the thyroid gland.

What is the purpose of the analysis for the hormone T3?

To determine the state of the thyroid gland, the endocrinologist necessarily gives the patient the direction for blood tests for three hormones - TTG, T4, T3. The study for triiodothyronine is considered very important, since it helps to minimize the diagnostic error.

For example, quite often working nodes in the nodal toxic goiter reproduce the hormone T3. Its amount can increase and with such diseases as diffuse toxic goiter and Basedova disease. If the result of the analysis shows a significant increase in the amount of triiodothyronine, the doctors diagnose "T3-toxicosis". This condition is quite difficult to treat with medications.

The norm of the hormone T3

Indicators of the norm depend on what equipment is used for the research. Each laboratory makes its choice in favor of certain equipment and necessary reagents. Therefore, it is impossible to define such a concept as the "triiodothyronine norm". The amount of it is considered normal if the results obtained fit within the reference boundaries (from 3.15 to 6.25 pmol / l), which are indicated on the laboratory blank. A form is formed on the computer, and the limits of the norm and the amount of the hormone are determined on it.

Increase of hormone T3

Many pathological conditions of the thyroid gland are accompanied by an increase in triiodothyronine. Often a person does not even notice such a deviation from the norm. Since T3 - a hormone is very active, increasing its amount in the blood causes the following symptoms:

• The person is annoying, he becomes nervous, aggressive, very quickly excited. This condition is accompanied by a feeling of constant fatigue.
• Start to shake fingers.
• The patient has an increased heart rate, tachycardia, the heart begins to work with interruptions. T3 - a hormone that contributes to the occurrence of extrasystole. Such a person feels very well and often complains to the doctor for malfunctioning of the heart.
• The patient begins to lose weight rapidly.

The analysis for determining the level of triiodothyronine is a rather complicated procedure. It is not uncommon for laboratories to make mistakes. You can additionally carry out a test to reveal the level of the other two hormones - T4 and TSH. If the results obtained indicate that TSH is normal, and T3 (hormone) is elevated, this usually indicates an error.

Also, the analysis will be unreliable even if the value of T4 is normal, and TSH and T3 are increased. If these results are obtained, then the analysis should be retaken, because when the hormone T3 increases, the level of TSH decreases, and T4 increases.

Decreased hormone T3

The level of triiodothyronine can decrease in case of disruption of the production of all the hormones that are produced by the thyroid gland. This condition occurs with the following diseases:

• Hashimoto's thyroiditis is a disease in which human immunity starts to kill some thyroid cells. They can not be restored, and most often they cease to work and produce hormones.
• Hyperthyroidism - such a disease occurs after taking some drugs aimed at treating diffuse and nodular toxic goiter. The most dangerous means in this regard are such thyreostatics as "Tyrozol", "Propitsil", "Mercazolil".
• The level of the hormone can be reduced after surgery for removing the entire thyroid gland or only part of it.
• Treatment with radioactive iodine also helps to reduce the level of triiodothyronine. Such therapy is aimed at removing diffuse toxic goiter.
• The level of the hormone can fall when you receive funds containing a large amount of iodine. They include "Amiodaron", "Kordaron" and others.

But not always a decrease in the level of the hormone T3 in the blood indicates the presence of the disease. This condition is typical for women waiting for a child, from 6 to 9 months of pregnancy.

It should be noted that the hormones T3 and T4, as well as TSH, decrease in a certain sequence. The first is always a decrease in the level of the hormone T4 and only after this falls triiodothyronine. This is due to the peculiarity of the organism, which is hedged as a result of the decrease in the hormone T3, since it is almost 10 times more active than T4.

Due to this, the patient is not so acutely aware of the consequences of hyperthyroidism. Thus, you can independently determine whether a laboratory error has been committed. If the level of triiodothyronine is lowered by the results of the analysis (and it is not important, it is the hormone T3 or general hormone), and T4 and TTG are within the normal range, then the data obtained should be checked in another laboratory and blood should be given again.

Conclusion

Thus, the deviation from the norm of thyroid hormones is a serious pathology, which is accompanied by a change in the state of health. At the same time, drowsiness may occur, memory and speech become worse, thoughts start to get confused, women have a malfunction in the menstrual cycle. With timely treatment, the level of hormones can be stabilized, the work of the thyroid gland and the whole organism comes to order.