Hormone T3: functions, norm and deviations
The content of the article:
- Free T3 hormone: what is responsible for in women and men
- Where is it produced
- Normal indicators
- T3 hormone increased
- T3 hormone lowered
- Video
The thyroid gland produces thyroid hormones - T3 (triiodothyronine) and T4 (thyroxine). They are responsible for many processes in the human body - basic metabolism, brain development, the work of the cardiovascular system.
The hormonal background in humans can be disrupted for various reasons, starting with the pathology of the thyroid and pituitary gland, ending with insufficient intake of iodine.
Triiodothyronine is a hormone produced by the thyroid gland that is involved in many processes in the body
Free T3 hormone: what is responsible for in women and men
The content of triiodironine in the blood is an important indicator of the functioning of the thyroid gland. Free triiodothyronine is the active form of the hormone, since it is not bound to blood proteins. Its level can both rise and fall. This often indicates the presence of thyroid disease.
The active form of triiodothyronine affects almost all processes in the body:
- Growth and development.
- Metabolism.
- Thermoregulation.
- Heart rate and regularity.
- Motility of the gastrointestinal tract.
In women, it indirectly affects menstrual function. With a deviation from the norm, menstruation becomes irregular, painful, the duration of the cycle changes - it lengthens or shortens.
Where is it produced
The hormone is produced in the follicles of the thyroid gland. Its production is regulated by thyroid-stimulating hormone (TSH) of the pituitary gland according to the principle of negative feedback:
- if T3 in the blood is higher than normal, TSH production is suppressed;
- if T3 in the blood is below normal, TSH production is activated.
Also, the hormone is formed during the breakdown of thyroxine (the cleavage of one iodine atom).
Normal indicators
If you suspect a thyroid dysfunction, you need to take several tests, one of them is the determination of free T3. Its normal level depends on age:
| Age, years | Norm, nmol / l |
| up to 20 | 1.23-3.23 |
| 20-50 | 1.08-3.14 |
| over 50 | 0.62-2.79 |
A deviation from the norm can be observed in both directions - both an increase and a decrease.
In most cases, testing the level of free triiodothyronine alone is insufficient. Additionally, the concentration of thyroxine, TSH is determined. Based on these data, it is possible to determine the functional diagnosis - hypothyroidism or hyperthyroidism.
T3 hormone increased
Many diseases of the thyroid gland can be accompanied by an increase in the level of triiodothyronine in the blood. At the same time, the basal metabolism is accelerated, more energy is formed. It affects almost all organs and systems.
| Target | Influence |
| Skin and mucous membranes | The skin becomes moist and warm to the touch |
| Gastrointestinal tract | Acceleration of motor skills is observed, which often manifests itself in the form of diarrhea |
| The cardiovascular system | An increase in the indicator greatly affects the heart. This manifests itself in the form of tachycardia - an increased heart rate. Prolonged tachycardia depletes the heart and increases its oxygen demand. Against this background, cardiac pathology may develop. |
|
Nervous system |
With an excess of triiodothyronine, emotional lability, irritability, tearfulness are observed |
| Thermoregulation | The effect on thermoregulation is manifested in the form of an increase in temperature. The temperature can be kept at the subfebrile level for a long time |
| Weight | Due to the acceleration of the basal metabolism, weight is lost despite the increased appetite |
For treatment, thyrostatic drugs are most often used.
T3 hormone lowered
Decreasing the rate also affects many systems. In this case, the following signs develop:
| Target | Influence |
| Skin and mucous membranes | The skin is dry and cold. Peripheral edema is common |
| Gastrointestinal tract | Decreased bowel motility, which manifests itself in the form of constipation |
| The cardiovascular system | The effect on the heart is manifested in the form of bradycardia |
| Nervous system | The effect on the nervous system is manifested in the form of lethargy, decreased cognitive abilities |
| Thermoregulation | There is a decrease in body temperature |
| Weight | Weight gain is due to a slowdown in basal metabolism and fluid retention |
A decrease in the indicator during pregnancy is dangerous, since under the influence of triiodothyronine, the laying of nervous tissue occurs. Deficiency of triiodothyronine and thyroxine can harm the unborn baby.
Treatment most often consists in the appointment of substitution therapy.
Video
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Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
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