The endocrine glands are non-ducted glands that secrete chemicals directly into the blood called hormones; To carry it to the target cells, the endocrine system, in cooperation with the nervous system, is responsible for maintaining the stability of the body’s internal environment. Hormones perform several functions in the body; It controls various cellular activities, including growth, development, reproduction, energy use and storage, and many other functions. The endocrine glands in the human body include: the pineal gland, the pituitary gland, the adrenal gland, the pancreas, the thyroid gland, the parathyroid gland, and the The thymus, the ovary, the testis, and there are other organs in the body that act as secondary endocrine glands, such as: the heart, liver, and kidneys.[1]


The thyroid gland is one of the endocrine glands in the human body. It is located below the larynx in the anterior lower part of the neck. It consists of two oblong lobes connected to each other by a narrow belt of tissue called the isthmus. The average weight of an adult ranges from 10-15 g. The thyroid gland contains many follicles lined with cystic cells, and it contains a fluid called colloidal substance that contains the protein thyroglobulin, from which thyroid hormones are made, namely: thyroxine, known for short (T4), and triiodothin: triiodothyronine (T3).[2]

Thyroid hormones

The thyroid gland makes two hormones, both containing thyronine and iodine: triiodothyronine, which contains three atoms of iodine, and thyroxine, which contains four atoms of iodine. The food we eat. The thyroid gland produces more thyroxine than triiodothyronine, so thyroxine can be converted to triiodothyronine in many tissues by an enzyme called deiodinase.[2] The functions of thyroid hormones are as follows:[3]

  • Regulating the body’s metabolism and energy production.
  • Regulating how much cells consume oxygen.
  • Regulating the functions of the brain, heart, kidneys, skin, hair, eyes, intestines, and muscles.
  • Regulating body temperature.
  • Regulating the functions of the brain and nerves, and regulating their development.
  • Regulating human growth.


A person develops hypothyroidism if the gland does not secrete an adequate amount of hormones, and women – especially those over 60 years old – are most susceptible to this disorder. The activity of the thyroid gland if it is neglected to treat some health problems, such as: obesity, joint pain, infertility, and heart disease.[4]


Hypothyroidism leads to a slowdown in the metabolism of the human body, which leads to a feeling of fatigue and weight gain. As the metabolism continues to slow in the body, the patient may have other signs and symptoms, including:[4]

  • Dry skin, puffiness of the face.
  • Exhaustion.
  • Excessive sensitivity to cold.
  • constipation;
  • Hair loss.
  • Low heart rate.
  • Muscle pain, weakness, and stiffness.
  • Hoarseness.
  • High level of cholesterol in the blood.
  • Joint pain and stiffness.
  • Irregular menstrual periods.
  • Heavy menstrual bleeding.
  • Depression.
  • Lots of forgetfulness.

the reasons

In a few cases, a person may develop hypothyroidism as a result of a congenital defect in the thyroid gland, a disorder in the pituitary gland, or a lack of iodine in food, and women may develop hypothyroidism during or after pregnancy, but these reasons are considered Uncommon causes, but the most important causes of hypothyroidism are:[4]

  • Immune system disorder: In some cases, the body suffers from an immune disorder; So that the immune system produces antibodies that damage the thyroid gland, causing it to suffer from a disease called Hashimoto’s thyroiditis, and this affects its production of hormones.
  • Treatment of hyperthyroidism: Treating an overactive thyroid gland with radioactive iodine or antithyroid drugs in some cases may lead to permanent hypothyroidism.
  • Thyroid surgery: removal of the thyroid gland, or a large part of it, leads to hypothyroidism, which requires the receipt of thyroid hormones for life.
  • Radiation therapy: Exposure to radiation used to treat head and neck cancer may cause an underactive thyroid gland.
  • Medications: Some medications, such as those used to treat mental disorders, cause hypothyroidism.

overactive thyroid gland

Hyperthyroidism is a disorder that causes the thyroid gland to secrete a large amount of thyroxine, which leads to an increase in metabolism in the body, and it is more prevalent in women than in men, and this condition can be easily treated when diagnosed, but ignoring it may cause serious problems. Treatment is taking anti-thyroid medications and radioactive iodine to slow the production of thyroid hormones.[5]


The main symptoms of an overactive thyroid gland are:[5]

  • Sudden weight loss.
  • Rapid heartbeat, and irregularity.
  • Increased appetite.
  • Feeling anxious and irritable.
  • sweating
  • Thyroid gland enlargement and swelling.
  • Excessive sensitivity to heat.
  • output disturbance; Especially frequent bowel movements.
  • Slight trembling in the hands and fingers.
  • Disruption of the pattern of menstrual periods.
  • Thinning of the skin.
  • Hair fragility and lack of density.
  • Sleep disturbance and difficulty.
  • muscle weakness;

the reasons

An overactive thyroid gland can be caused by a number of medical conditions, including:[5]

  • Infection with Graves’ disease, the most common cause of hyperthyroidism, a disease represented by the extraorbital protrusion of the eyeball, which occurs as a result of a disorder of the immune system that produces antibodies that mistakenly attack the thyroid gland, and sometimes attack the tissue behind the patient’s eyes.
  • Incidence of toxic adenoma.
  • Plummer’s disease, or hyperthyroidism.
  • Thyroiditis.

the reviewer

  1. ↑ Regina Bailey (12-6-2018), “Endocrine System Glands and Hormones”, www.thoughtco.com, Retrieved 8-11-2018. Edited.
  2. ^ a b “Thyroid gland”, www.britannica.com, 11-12-2018, Retrieved 7-12-2018. Edited.
  3. ↑ Alina Bradford (20-4-2017), “Thyroid Gland: Facts, Function & Diseases”, www.livescience.com, Retrieved 8-11-2018. Edited.
  4. ^ abt “Hypothyroidism (underactive thyroid)”, www.mayoclinic.org, 5-16-2018, accessed on 8-11-2018. act.
  5. ^ a b c “Hyperthyroidism (overactive thyroid)”, www.mayoclinic.org, 5-16-2018, retrieved 8-11-2018. act.

Research on the thyroid gland

writing – on the date : – Last updated: 2022-06-21 11:33:01