Free T4 - the norm in a woman's blood

2024 Author: James Gerald | [email protected]. Last modified: 2024-01-18 00:05

Free form thyroxine (tetraiodothyronine, T4), or propionic acid, is one of the most important hormones secreted by the thyroid gland. T4 is a derivative of L-tyrosine with the addition of 4 iodine molecules.

T4 itself is biologically inactive. It is activated by the selenium-dependent monodeiodinase enzyme. This enzyme converts T4 into the form of triiodothyronine with high biological activity.

How thyroid hormones are synthesized

In the ratio of the total hormonal level, in the amount produced by the thyroid gland, 4/5 of the part is T4, 1/5 of the part is triiodothyronine. Thyroxine is synthesized with the participation of thyrotropin, produced by the tissues of the thyroid gland. It accumulates for a long time due to low functional activity.

The total number of T4, which must be produced by the thyroid gland, is due to its content in the blood. These norms of free T4 in women by age are given in the table with the units of pmol / l.

At a high concentration of thyroxine, iron releases less of it. With a low content of T4, the thyroid gland releases it more actively until a normal concentration is obtained, which ensures the life of a woman. The synthesis of thyroxine is due to external factors. So, with prolonged hypothermia, a woman's production increases.

Functions of T4 in a woman's body

Thyroxine affects the tissues of the body at the cellular level. There are no special cells that show a specific need for it. The main function of T4 is to enhance metabolic processes.

T4 affects:

• regulation of body temperature;
• normalization of thyroid function;
• the formation of bone structure;
• acceleration of metabolism;
• tissue growth;
• correct development of the female body;
• development of the reproductive system;
• the rate of reproductive functions;
• increase in heart rate;
• thickening of the mucus layer inside the uterus;
• increased regeneration of nerve tissues.

This effect becomes possible due to the activation of protein production. The rate of free T4 in women by age can be found from the table in pmol / l units.

What species is T4 in the body?

The body has T4 in 2 types:

• free, highly biologically active;
• connected, inactive.

Of the total concentration of thyroxine, 99.9% is T4 of a bound species, 0.1% is free. Therefore, laboratory assistants usually determine 2 parameters: total concentration, indicators of a free species.

Deciphering of the analysis data in women is carried out by an endocrinologist, a gynecologist, taking into account the age of the patient. It is by age that the doctor determines the normal values of T4. In laboratories, synthetic T4 has been created, which can easily restore thyroxine deficiency. The norms of free T4 in women by age are shown in the table, in pmol / l.

Woman's age	The norm of free T4 values according to the woman's age, in pmol / l
Over 20 years old	10, 5 – 21, 8
Over 30 years old	9, 0 – 22, 0
50-60 years old	7, 0 – 15, 4
60-70 years old	4, 0 – 13, 5
After 70 years	4, 0 – 12, 4

The functions of the whole body of a woman depend on the correct functions of the thyroid gland, the amount of synthesized thyroxine. From the table you can find out the rate of free T4 in women by age in pmol / l.

Increased T4 values of the free form mean the appearance of hyperthyroidism in a woman, which is accompanied by a pathologically high production of thyroid hormones. A decrease in the synthesis of free T4 means the development of hypothyroidism. It is more often diagnosed in women over 55. In this disease, there is a decrease in the mass of thyroid tissue, which leads to an even greater decrease in the synthesis of T4.

Both conditions require medical correction, restoration of hormonal levels. In this case, you cannot do without the help of an endocrinologist. Therapy with hormonal drugs is prescribed under the supervision of a physician.

Increase the thyroxine content by prescribing:

• Levothyroxine;
• Furosemide;
• Amiodarone;
• Anazole;
• Propranolol;
• Propylthiouracil.

Reduce high T4 values by prescribing drugs:

• Octreotide;
• Phenytoin;
• Methadone;
• Carbamazepine;
• lithium media;
• thyreostatics;
• Clofibrate.

The necessary drug, suitable in a particular case, is determined by the doctor according to the woman's age, her body weight, thyroxine indicators.