Thyroglobulin: Definition, Importance, Function and Related Diseases

It is a dimeric protein produced by the follicular cells of the thyroid and used completely within the thyroid gland.

The thyroglobulin protein represents approximately half the protein content of the thyroid gland .

Human TG (HTG) is a homodimer of subunits that each contain 2768 synthesized amino acids (a short signal peptide can be removed from the N-terminus in the mature protein).

Importance

The protein is a precursor of the thyroid hormones; These are produced when tyrosine residues of thyroglobulin are combined with iodine and the protein is subsequently cleaved.

Each thyroglobulin molecule contains approximately 100-120 tyrosine residues, but only a small number of these are subject to iodination by thyroperoxidase in the follicular colloid.

Therefore, each molecule of Tg forms only about 10 molecules of thyroid hormone.

Function

Thyroglobulin (Tg), which is well known as the macromolecular precursor of thyroid hormone, is the most important and abundant protein produced and stored in thyroid follicles.

In the last decade, in addition to its well-established role as a precursor to thyroid hormone, we have revealed important new functions for Tg.

Thyroglobulin can serve as a negative regulator of genes related to thyroid function and an inducer of thyrocyte growth.

It is the most important and abundant protein in the thyroid follicles, it is well known for its essential role in the synthesis of thyroid hormone.

In addition to its conventional role as a precursor to thyroid hormones, we have discovered a new function of Tg as an endogenous regulator of follicular function in the last decade.

The recently discovered negative feedback effect of Tg on follicular function observed in the thyroid of rats and humans, provides an alternative explanation for the observation of follicle heterogeneity.

Given the essential role of regulatory effects of Tg, we consider that dysregulation of normal Tg function is associated with multiple human thyroid diseases, including autoimmune thyroid disease and thyroid cancer.

In addition, extrathyroid Tg can play a regulatory role in other organs.

An additional exploration of the action of Tg is needed, especially at the molecular level, to obtain a better understanding of the physiological and pathological roles of the same.

The new functions of thyroglobulin have been recognized during the last decade, including a negative feedback effect of Tg on thyroid function through the regulation of the expression of genes essential for the synthesis of thyroid hormone, an effect of promotion of the thyroid hormone. cell growth and extrathyroid functions.

However, our knowledge of the action of Tg at the molecular level and its possible participation in thyroid pathology (including autoimmune diseases and cancer) is much less complete.

More research is needed to explore the mechanism of Tg recognition by thyrocytes, the signaling pathways responsible for the action of Tg and the potential role of Tg in the development of all types of thyroid diseases.

Related diseases

The following conditions are associated with elevated thyroglobulin levels:

Thyroid cancer:

Thyroid cancer is a disease that occurs when abnormal cells begin to grow in the thyroid gland.

The thyroid gland is shaped like a butterfly and is located on the front of the neck.

It produces hormones that regulate the way your body uses energy and that help your body to work normally.

Experts do not know what is the exact cause of thyroid cancer. But like other cancers, changes in the DNA of your cells seem to play an important role.

These changes in DNA can include changes that are inherited and those that happen as you get older.

People who have been exposed to a lot of radiation have a higher chance of getting thyroid cancer.

Radiation treatment located in the front of your head, neck or chest (especially during childhood) may put you at risk for thyroid cancer.

There are 4 types of thyroid cancer:

  • Follicular carcinoma: is more common in countries where people do not get enough iodine in their diet and does not tend to spread to the lymph nodes.
  • Papillary carcinoma: This type is found in a single lobe of the thyroid gland and tends to grow very slowly.
  • Medullary carcinoma: is a cancer that begins in a group of thyroid cells called C cells and is very rare. C cells produce calcitonin, not thyroid hormone.
  • Anaplastic carcinoma: This carcinoma is a rare form of thyroid cancer and commonly metastasizes rapidly to other organs of the body, such as the lungs or kidneys, which makes it very difficult to treat.

There are many ways to treat thyroid cancer, but surgery is the main treatment.

The goal of treatment for thyroid cancer is to get rid of the cancer cells in your body.

How the treatment is determined depends on your age, the type of thyroid cancer you have, the stage of your cancer and your general health, and you may need more than 1 type of treatment.

The most common treatments for thyroid cancer are those usually used for all types of cancer. These include:

  • Surgery.
  • Treatment of radioactive iodine.
  • Radiation.
  • Chemotherapy.

Tiroiditis de Hashimoto:

Hashimoto’s thyroiditis, also known as chronic lymphocytic thyroiditis or Hashimoto’s disease, is an autoimmune disease in which the thyroid gland is gradually destroyed.

At the beginning there may be no symptoms. Over time, the thyroid may enlarge to form a painless goiter.

Some people eventually develop hypothyroidism with the weight gain that accompanies it, feeling tired, constipation, depression and general pain.

The immune system attacks the thyroid in people who suffer from this condition.

The exact cause of Hashimoto is not known, but it is believed that many factors play a role. They include:

  • Genetics: It is common in people with Hashimoto’s thyroiditis, that their relatives have thyroid problems.
  • Excess iodine: research suggests that certain medications and too much iodine, a trace element required by your body to produce thyroid hormones, can trigger thyroid disease in susceptible people.
  • Exposure to radiation: Increased cases of thyroid disease have been reported in people exposed to radiation, including atomic bombs in Japan and the type of radiation used to treat a form of blood cancer called Hodgkin’s disease .

Hashimoto symptoms may be mild at first or take years to develop.

The first most common sign in the disease is known as goiter, an enlarged thyroid.

Other symptoms of an underactive thyroid due to Hashimoto may include:

  • Weight gain.
  • Fatigue.
  • Paleness or swelling of the face.
  • Pain in the joints and muscles.
  • Constipation .
  • Difficulty getting pregnant.
  • Pain in the joints and muscles.
  • Hair loss or thinning, brittle hair.
  • Irregular or heavy menstrual periods.
  • Depression .
  • Decreased heart rate

The best treatment for this disease is to use medications to regulate hormone levels and restore normal metabolism, since this condition has no cure.