Hyperthyroidism: Causes & Symptoms

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The thyroid gland produces hormones which include tri-iodothyronine (T3) and thyroxine (T4). T3, T4 hormones regulate body metabolism. The thyroid hormones in the blood determine the metabolic rate. Pituitary gland located in the brain regulates the production of these hormones by secreting a chemical called thyroid stimulating hormone (TSH).

What is Hyperthyroidism?

Hyperthyroidism refers to the state of overactivity of the thyroid gland in the body. It is a condition in which the thyroid gland, that is shaped like a butterfly, produces excess thyroid hormone and is also sometimes referred to as thyrotoxicosis. These hormones play a significant role in keeping the body energized and ensuring overall growth and smooth functioning of various critical processes and metabolism of the body.



According to the University of Maryland Medical Center, thyroid hits more women as compared to men and typically happens after 60 years. Causes of hyperthyroidism include:

  • Graves’ disease: Graves’ disease is an autoimmune inflammatory disease and is the most commonly found reason for hyperthyroidism. It is characterized by the retraction of upper eyelids along with swelling and erythema. Graves’ disease is caused by the release of excess thyroid hormone by the thyroid gland. This happens because of the antibodies present in the blood, stick to particular activating sites on the gland, which triggers the growth of thyroid gland resulting in excess secretion.
  • Toxic nodular goiter: Another reason for hyperthyroidism to occur is the gradual growth of lumps or nodules in the thyroid gland. These lumps lose their regulatory mechanism and boost the activity of thyroid gland resulting in excess secretion of the thyroid hormone into the blood. It is also known as multinodular goiter.
  • Immune system malfunction: Some viral infection in the thyroid or immune system may also be a cause of hyperthyroidism. This condition also known as thyroiditis can cause leakage of stored thyroid hormone by the gland.
  • Excess of iodine: Ingestion of excess iodine intentionally or inadvertently from various sources such as disinfectants and X-ray contrast mediums can also lead to hyperthyroidism in vulnerable individuals.


Thyroid hormones contribute significantly to the rate of the processes running in the body. Excess thyroid hormone has a tendency to accelerate the functions of the body.

Due to the enlarged thyroid gland, people suffering from Graves’ disease may experience swelling in front of the neckline also known as ‘goiter’. Some patients may have raised upper eyelids making their eyes look enlarged and protruding.

Individuals suffering from hyperthyroidism might also experience other symptoms such as:

  • Weakness in the upper arm and thigh muscles
  • Heart palpitation
  • Nervousness
  • Intolerance to heat
  • Increased sweating
  • Trembling in hands
  • Shortness of breath
  • Anxiety
  • Irritability
  • Insomnia
  • Thin and fragile hair
  • Repeated bowel movement
  • Loss of weight even with a good appetite

Women suffering from hyperthyroidism may experience irregular menstrual cycle with the light menstrual flow. Overactive metabolism as a result of hyperthyroidism may primarily lead to an over-energized body. However, eventually, the body breaks down with the persisting hyperthyroidism leading to general body fatigue and tiredness.

Difference between Hyperthyroidism & Hypothyroidism

Hypothyroidism refers to an underactive thyroid, whereas hyperthyroidism refers to an overactive thyroid. Both these conditions have opposite effects on the body – while hypothyroidism causes depression, weight gain, and tiredness; hyperthyroidism causes anxiety, increased heartbeats, and weight loss.

In hypothyroidism, the thyroid gland slows down the production of hormones and thereby results in slowing down the metabolism. Hypothyroidism is mostly caused by a condition called Hashimoto’s disease, in which the body starts attacking its own immune system. This prevents the production of hormones by the thyroid gland.

In hyperthyroidism, the thyroid gland increases the production of hormone and thereby results in an overproduction of the hormones. This causes an increase in the metabolism. Hyperthyroidism can most commonly be seen in the form of Grave’s disease that causes goiter and inflammation of the eyes.

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