The thyroid gland performs one of the main functions in the body; it produces hormones that are extremely important for the normal functioning of a person. One of these hormones is free T3 (triiodothyronine). The number three in the abbreviation denotes the number of iodine atoms in its molecule. It is formed by follicular cells as a result of the cleavage of one iodine atom from thyroxine (T4). 

Functional value of T3 free

The main role of free T3 is to stimulate tissues to absorb oxygen and activate metabolic functions. Together with the T3 hormone, the bound forms the general T3 index. However, free T3 hormone is considered a more truthful indicator, with the exception of intensive care patients. In this case, reliability will be obtained if blood tests are performed for total T3 content.

Free T3 is the active link of T3 in general. Its increased concentration in blood atoms does not affect the decrease in the amount of protein, because it is freely movable and does not interact with the carrier protein.

It is produced by follicular cells and released into the bloodstream. When it enters the bloodstream, it begins to interact with protein molecules, which facilitate its movement to the sites of oxygen absorption.

You can find out what the hormone is responsible for from the list of its functions below:

• accelerates the absorption of oxygen by tissues, except for the cellular tissues of the brain and glands of the genital organs;
• increases heat generation in the human body;
• promotes intensive protein metabolism in blood cells;
• increases the accumulation of glucose in the blood;
• lowers the concentration of cholesterol and triglycerides;
• stimulates the production of vitamin A in the liver;
• stimulates the excretion of calcium from the blood
• stimulates the contractions of the muscles of the heart;
• forms alveoli in infants;
• enhances the undulating contraction of the intestinal walls, contributing to the normal excretion of contents;
• increases the formation of red blood cells;
• performs control of exchange in bone tissues;
• enhances the function of removing harmful substances and drugs from the blood.

The direction for conducting analyzes is given, as a rule, to identify the level of concentration of free T3, since it is its normal concentration in the blood that is of particular importance for the activity of the whole organism. The indicator determines the pathology of the thyroid gland.

Hormone test

First of all, the endocrinologist gives the patient a direction to conduct an analysis for the hormones T3, T4, TSH. These are the main studies in determining disorders in the thyroid gland. Often, in order to save their own budget, a blood test for free T3 content is not carried out, however, this is a wrong decision, which leads to an error in the diagnosis.

Note that in case of nodular toxic goiter disease, the nodes of the thyroid gland working in aggregate produce free triiodothyronine. The disease passes with clearly identified signs and is very slowly eliminated by drug therapy. Also, an increased level of hormone levels indicates diseases such as Graves’ disease or diffuse toxic goiter. If the T3 hormone St. significantly exceeded the limit, doctors diagnosed T3 toxicosis.

The level of concentration of the hormone is established by blood from a vein. The exact value can be obtained if you follow important rules:

• the patient is obliged to donate blood on an empty stomach, otherwise the indicator will not be reliable;
• one month before the procedure, all medications containing thyroid hormones are canceled;
• five days before the study, the patient must exclude all physical activity;
• the last time you are allowed to eat 8 hours before the analysis.

In general, decoding analyzes is a rather complicated process, since the result depends on the equipment on which the analysis is carried out. The rate is determined according to the data indicated on the laboratory form, which is printed from a computer program. If the indicators of the hormone are written by hand, it is considered that the analysis was not carried out correctly, without the appropriate reagents or equipment.

As the data from the form show, the normal level of the hormone should fit into certain thresholds of values, this is from 2.6 to 5.7 pmol / l.

The normal concentration of the hormone in a child has a number of differences from an adult. For example, before adolescence, rates are allocated separately for boys and separately for girls. In the table below, you can familiarize yourself with the boundaries of the values ​​for the age and gender of the child:

Elevated level

When the free T3 hormone is elevated, the patient experiences:

• increased sweating;
• the skin becomes warm and moist to the touch;
• hair is thinning;
• increased frequency of contraction of the heart muscles;
• violation of the heartbeat (arrhythmia);
• increased appetite;
• increased undulating contraction of the intestinal muscles, there is a tendency to diarrhea;
• increased systolic blood pressure;
• sharp weight loss;
• the appearance of nervousness, emotional instability;
• muscle weakness;
• fast fatiguability;
• shaking hands;
• widening of the eye slits, protrusion of the eyeballs;
• the content of calcium in blood cells increases;
• irregular menstruation.

All of the above symptoms mean that their manifestation indicates the presence of a number of diseases, such as toxic goiter, adenoma, melama, pathological processes in the liver of a chronic form, nephrotic syndrome, thyrotropinoma, thyroid dysfunction in the postpartum period.

An increased level of free T3 is also manifested with excessive thyroid function (thyrotoxicosis), with iodine deficiency. Or with prolonged use of drugs that have a direct effect on the degree of hormone content (oral contraceptives, estrogens, etc.).

Reduced level

If the patient’s level of free T3 hormone is lowered, the following symptoms are observed:

• hair loss;
• weakness of the eyelids;
• decrease in the field of vision;
• loss of appetite;
• weakening of intestinal motility, frequent constipation;
• inhibition of actions;
• muscle weakness;
• decrease in the contraction of the heart muscles;
• impotence (in men);
• frequent with profuse menstruation (in women);
• an increase in cholesterol.

The listed violations reflect a low level of the hormone, which indicates the presence of diseases such as primary hypothyroidism of congenital origin (underdevelopment or complete absence of the thyroid gland), acute iodine deficiency, acute thyroiditis, pathology of internal organs with a severe course, chronic liver disease, lack of protein …

Note that not always a lowered hormone indicator indicates the presence of various diseases. There is a decrease in its concentration in expectant mothers in the third trimester of pregnancy. As a rule, with the birth of a baby, the indicator will return to normal.

Having determined the results of the analysis, you should not make hasty conclusions and make a diagnosis yourself, relying only on the free T3 indicator. Often, for accurate diagnosis, it is required to check the status of the concentration of hormones in the body as a whole. It is also important to say that drug therapy is prescribed only by the attending physician, evaluating the test data, making an examination and determining the individuality of the organism.