What is Thyroid Gland?
The thyroid gland is a butterfly-shaped gland located in our neck in front of the trachea. The thyroid gland, which weighs approximately 20 g, consists of the right lobe (right wing), left lobe (left wing) and the middle part called the isthmus. The dimensions of the right lobe and left lobe of the thyroid are approximately 50*30*20 mm. These dimensions may differ from person to person. An enlargement in the thyroid gland (goiter) may be in the gland itself, or it may be due to the nodule (mass) in the gland.

What are the Functions of the Thyroid Gland?

The task of the thyroid gland is the production and secretion of thyroid hormones into the blood. The thyroid gland produces hormones called t4 and t3. Thyroid hormones have functions such as proper execution of metabolism, maintaining body temperature, development of cells, development of embryo in pregnant women. The normal execution of thyroid hormones is of great importance for a healthy metabolism. When thyroid hormones are secreted insufficiently, that is, when the thyroid is underactive (Hypothyroidism), complaints such as fatigue, low energy, constipation, easy cold, forgetfulness, edema, dry skin and hair loss occur. In case of excessive secretion of thyroid hormones or overworking of the thyroid, complaints such as palpitation, tremor in the hands, weight loss, nervousness, sweating, menstrual irregularity and hair loss occur.

What Do Thyroid Tests Mean?

When determining whether the thyroid gland is functioning normally, first of all, the hormones in the blood are checked. The main hormones secreted from the thyroid gland are free T4 and free T3 hormones. While these hormones are carried in the blood, they bind to carriers such as thyroid binding globulin and albumin. Total T4 and Total T3 measurement refers to the measurement of the levels of free thyroid hormones bound to carrier proteins in the blood. Since the level of carrier proteins such as thyroid binding globulin and albumin is affected by many factors such as liver diseases, birth control drugs, obesity, male hormones, measurement of free T4 and free T3 hormones is used in clinical practice.

Another important test in evaluating whether the thyroid gland is functioning normally is TSH (Thyroid Stimulating Hormone). TSH is secreted from the pituitary gland and monitors thyroid hormone levels in the blood. When thyroid hormones are insufficient (hypothyroidism), the TSH rises to high levels. The rise of TSH is actually a message and command to the thyroid gland. TSH has an increasing effect on hormone production and release from the thyroid gland, and has an enlarging effect on the thyroid gland. In fact, the increase in TSH secreted by our brain is an order for more thyroid hormone production from the thyroid gland. However, if the thyroid gland cannot respond to this command of TSH by raising thyroid hormones, that is, if thyroid hormones cannot increase production despite the increase in TSH, thyroid laziness, that is, hypothyroidism, has begun. (Click for detailed information on hypothyroidism.)

The decrease in TSH hormone occurs when the thyroid is overworked (hyperthyroidism). When the thyroid is overworked (hyperthyroidism), our brain tries to correct the overactivity of the thyroid by reducing the release of TSH from the pituitary gland in order to reduce the level of thyroid hormones in the blood. However, in cases such as Graves' disease (toxic goiter), toxic adenoma, and toxic multinodular goiter, the TSH hormone will remain constantly low because the thyroid gland itself produces excess thyroid hormone. (Click for detailed information on toxic goiter.)

Other important tests with blood tests in the evaluation of the thyroid gland are thyroid antibodies. Anti-TPO and Anti-TG are antibodies that increase especially in Hashimoto's disease and cause hypothyroidism. These antibodies increase as a result of the attack of the immune system (autoimmunity) against the thyroid peroxidase and thyroglobulin molecules, which are two important molecules in the thyroid gland. These antibodies are often associated with a family history of thyroid disease, that is, they show a genetic predisposition. As a result of the destruction of the thyroid gland by Anti-TPO and Anti-TG antibodies, the thyroid gland may lose its function and this may result in insufficient production of thyroid hormones (Hypothyroidism).

TSH receptor antibody (TRAB) is one of the important antibodies formed by the immune system against the thyroid gland. The immune system creates a foreign vision reaction against the TSH receptor on the thyroid gland. In other words, it creates a reaction similar to the reaction it creates against a foreign bacteria or virus against the TSH receptor, and as a result, the TSH receptor is constantly stimulated, causing the thyroid gland to work excessively. Thus, the thyroid gland starts to work excessively and produces excessive amounts of thyroid hormone and causes the formation of Toxic Goiter. TSH receptor antibody (TRAB) is an important indicator in the diagnosis of Graves' disease (Toxic Goiter), in the follow-up of the disease, in monitoring the severity of the disease and in eye involvement (Graves' Ophthalmopathy). (Click for detailed information TSH Receptor Antibody – TRAB)

In addition to blood tests for thyroid hormones, another important examination that shows the health of the thyroid gland is Thyroid Ultrasonography.

With Thyroid Ultrasonography;

- The shape of the thyroid gland,

- Enlargement (Goiter) or Shrinkage (Atrophy) of the Thyroid Gland

- Whether there is inflammation in the thyroid gland (Hashimoto etc.)

- Whether there are masses called nodules in the thyroid gland

- Whether the Nodules in the Thyroid Gland are benign or malignant

- Whether Thyroid Nodules are at risk of cancer

- Decision to perform thyroid biopsy from thyroid nodules

 - The blood supply of the thyroid gland and thyroid nodules is examined.

 

Tests Performed in Thyroid Gland Examination

- TSH, fT4 (Free T4), fT3 (Free T3)

- Anti-TG, Anti-TPO, TSH Receptor Antibody

- Tyroglubulin

- Urine Iodine

- Selenium

- Thyroid Ultrasonography

- Thyroid Scintigraphy

Hypothyroidism

Hashimato's Disease

Hyperthyroidism

Thyroid Nodules

Thyroid Cancer

Subacute Thyroiditis