Hormones And Biochemistry

If the free T4 is above the norm

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Analyzes for hormones such as TSH, T3 and T4, as well as antibodies to thyroid peroxidase and thyroglobulin are most often prescribed in cases where there are suspicions of various functional thyroid disorders or when treating them for monitoring and correcting maintenance therapy.

T4( like T3) is a hormone( a biologically active substance) belonging to triiodothyronines. It consists of an amino acid - tyrosine, and iodine atoms( got one of its names in connection with the number of these very atoms - 4, and in T3, respectively, 3).Other names are thyroxine or tetraiodothyronine. Its structure is simple enough, due to what it is simply revealed in the blood or synthesized artificially.

The structure of the thyroid gland

In the human body, it is produced with the help of thyroid cells - thyrocytes. They capture amino acids and iodine atoms, and produce thyroglobulin, which is a precursor of thyroxine - thyroglobulin. The latter, in turn, accumulates in the follicles of the thyroid gland. When there is an organism's need for T4, the thyroglobulin is broken into small particles and enters the bloodstream as a ready-made biologically active substance.

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The action of thyroxin in the human body

Its main action is the enhancement of catabolism, that is, the acceleration of processes that take place with the release of energy from body stores.

If you take 200 micrograms of T4 per day, you can easily see its effect on the human body, because the following symptoms will appear:

  • appearance of tachycardia,
  • irritability,
  • weight loss.

This experiment does not prove the harmfulness of this biologically active substance on the human body, since these symptoms appear only in case of an overdose. Normally, he is responsible for the normalization of metabolism and the breakdown of fats, regulates the excitability of the nervous system and the heart rhythm.

Weight loss

It should be remembered that tetraiodothyronine is much less active than T3( triiodothyronine).T3 has three iodine atoms, and is formed mainly from tetraiodothyronine. A small amount of it synthesizes the thyroid gland.

These biologically active substances are called thyroid hormones, because they are synthesized by the thyroid gland, while TSH is synthesized in the pituitary gland. This should be taken into account in the appointment of therapy for violations of the level of thyroid hormone concentration in the blood.

T4 in the blood

In the bloodstream, tetraiodothyronine is most often in a state of communication with a protein whose function is transporting. Thyroxin-binding globulin( TGS) captures the molecule of thyroxin and transports it to the necessary places. The TSH molecule binds T4 as soon as it is produced by the thyroid gland cells, but a small percentage remains unbound, or free. It is the free tetraiodothyronine molecules that have the most pronounced effects. The amount of free and bound hormone is called the common T4.

The need to determine free thyroid hormones in analysis is due to the fact that they exert the main influence on the body of all thyroid hormones. In this case, TTG and tetraiodothyronine exert the most active influence, since TSH controls the thyroid gland, and T4 is its main biologically active substance.

Assay for the hormone T4

The blood test for thyroid hormones is one of the most commonly prescribed in the practice of an endocrinologist. They are appointed in a variety of combinations. The reasons for this may be:

Blood test

  • saving the financial capabilities of the patient;
  • more detailed study of thyroid function;
  • in some cases, one or two indicators suffice.

In the case of the first referral of the patient to the endocrinologist and in the absence of physical disorders and complaints, only TSH is most often checked, but sometimes it is recommended to take T3, T4 for more reliable information.

In the case of therapy of the early stage of Graves' disease, implying a decrease in activity of the hormonal background by thyreostatics, tests for T3 and tetraiodothyronine are recommended.

With prolonged therapy, which is to reduce thyroid function with thyroxine, it is recommended to examine blood on TSH.

In pregnancy, the value of free tetraiodothyronine can change, because TSH may decrease( due to the production of chorionic gonadotropin), which leads to an increase in the concentration of tetraiodothyronine in the blood. Therefore, during pregnancy, the levels of TSH, tetraiodyronine should be monitored.

Norm T4

The norm values ​​depend on the laboratory and their methods of determination in the blood. Remembering the norm of the indicators is not necessary, since each laboratory is often indicated in the results of the study.

Blood test

The free tetraiodothyronine level is 9-19 pmol / l( assuming the use of third generation analyzers).

The rate of total tetraiodothyronine is often associated with the general condition of the patient. For example, during pregnancy, the indices are increased, but are of a functional nature.

Increase in T4

Increase in tetraioditronin results in the following symptoms:

  • increased sweating, fatigue,
  • , irritability,
  • tachycardia, arrhythmia,
  • tremor of upper extremities,
  • weight loss.

If the level of tetraiodothyronine is increased, then the intensive disintegration of the body's energy reserves develops, which leads to increased release of energy. The result of these processes is a decrease in the amount of fat, and excess energy is sent to other places, thereby strengthening normal processes - excitability, cardiac contractions and others. As a result, a person grows thin, but such a decrease in mass is not useful and not physiological, since it occurs against a background of disturbance of the body's homeostasis. If the violation of the hormonal background will be of a long duration, there may be irregularities in the bone tissue, severe fractures can develop.

If a reduction or increase in free tetraiodothyronine is found in the assays, it is recommended that the endocrinologist be immediately consulted, since such indicators may indicate functional thyroid dysfunction. In some cases, in addition to drug therapy, surgery may be required.

T4 in pregnancy

Pregnancy

The level of tetraiodothyronine in pregnancy is quite significant, because it affects the development of the nervous system of the fetus in the first trimester. In women, the norm of this hormone is the same as that of men, however, in pregnancy, the parameters of total tetraiodothyronine should not be determined, as it usually rises, which is the norm. This is due to the fact that during pregnancy, thyroxine-binding globulin is produced in a larger amount, and binds most of the tetraiodothyronine of the blood, which does not have activity in the bound state. This means that this situation does not require correction and treatment.

A more important analysis during pregnancy is the determination of free tetraiodothyronine, while its norm should be fairly strictly observed. Decrease in its indices should be made under careful control, that is, treatment of this condition should be done very carefully and slowly, so as not to harm the fetus.

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