What is Hyperthyroidism

Hyperthyroidism is when the thyroid gland is too active (overactive). The thyroid gland is a small gland located in the lower front part of the neck, just in front of the windpipe (trachea).

This gland makes hormones that help control how the body uses food for energy (metabolism) as well as how the heart and brain function. These hormones also play a role in keeping your bones strong. When the thyroid is overactive, it produces too much of a hormone called thyroxine.

7 Interesting Facts of Hyperthyroidism

  1. Clinical state induced by excessive production and secretion of thyroid hormones by an overactive thyroid gland
  2. Causes tachycardia, tremor or hyperreflexia, increased sweating, exophthalmos, lid retraction, and lid lag
  3. Most common causes of hyperthyroidism are Graves disease, toxic multinodular goiter, and toxic uninodular goiter
  4. TSH is the most sensitive test for hyperthyroidism (level decreased)
  5. Free T₄ level is high in most cases of overt hyperthyroidism
  6. T₃ level is often elevated to a greater extent than T₄ level in severe hyperthyroidism
  7. Differentiated with thyroid function tests (decreased TSH level with elevated T₄ and T₃ levels)

What are the causes?

This condition may be caused by:

  • Graves’ disease. This is a disorder in which the body’s disease-fighting system (immune system) attacks the thyroid gland. This is the most common cause.
  • Inflammation of the thyroid gland.
  • A tumor in the thyroid gland.
  • Use of certain medicines, including:
    • Prescription thyroid hormone replacement.
    • Herbal supplements that mimic thyroid hormones.
    • Amiodarone therapy.
  • Solid or fluid-filled lumps within your thyroid gland (thyroid nodules).
  • Taking in a large amount of iodine from foods or medicines.

What increases the risk?

You are more likely to develop this condition if:

  • You are female.
  • You have a family history of thyroid conditions.
  • You smoke tobacco.
  • You use a medicine called lithium.
  • You take medicines that affect the immune system (immunosuppressants).

What are the signs or symptoms?

Symptoms of this condition include:

  • Nervousness.
  • Inability to tolerate heat.
  • Unexplained weight loss.
  • Diarrhea.
  • Change in the texture of hair or skin.
  • Heart skipping beats or making extra beats.
  • Rapid heart rate.
  • Loss of menstruation.
  • Shaky hands.
  • Fatigue.
  • Restlessness.
  • Sleep problems.
  • Enlarged thyroid gland or a lump in the thyroid (nodule).

You may also have symptoms of Graves’ disease, which may include:

  • Protruding eyes.
  • Dry eyes.
  • Red or swollen eyes.
  • Problems with vision.

How is this diagnosed?

This condition may be diagnosed based on:

  • Your symptoms and medical history.
  • A physical exam.
  • Blood tests.
  • Thyroid ultrasound. This test involves using sound waves to produce images of the thyroid gland.
  • A thyroid scan. A radioactive substance is injected into a vein, and images show how much iodine is present in the thyroid.
  • Radioactive iodine uptake test (RAIU). A small amount of radioactive iodine is given by mouth to see how much iodine the thyroid absorbs after a certain amount of time.

How is this treated?

Treatment depends on the cause and severity of the condition. Treatment may include:

  • Medicines to reduce the amount of thyroid hormone your body makes.
  • Radioactive iodine treatment (radioiodine therapy). This involves swallowing a small dose of radioactive iodine, in capsule or liquid form, to kill thyroid cells.
  • Surgery to remove part or all of your thyroid gland. You may need to take thyroid hormone replacement medicine for the rest of your life after thyroid surgery.
  • Medicines to help manage your symptoms.

Follow these instructions at home:

  • Take over-the-counter and prescription medicines only as told by your health care provider.
  • Do not use any products that contain nicotine or tobacco, such as cigarettes and e-cigarettes. If you need help quitting, ask your health care provider.
  • Follow any instructions from your health care provider about diet. You may be instructed to limit foods that contain iodine.
  • Keep all follow-up visits as told by your health care provider. This is important.
    • You will need to have blood tests regularly so that your health care provider can monitor your condition.

Contact a health care provider if:

  • Your symptoms do not get better with treatment.
  • You have a fever.
  • You are taking thyroid hormone replacement medicine and you:
    • Have symptoms of depression.
    • Feel like you are tired all the time.
    • Gain weight.

Get help right away if:

  • You have chest pain.
  • You have decreased alertness or a change in your awareness.
  • You have abdominal pain.
  • You feel dizzy.
  • You have a rapid heartbeat.
  • You have an irregular heartbeat.
  • You have difficulty breathing.


  • The thyroid gland is a small gland located in the lower front part of the neck, just in front of the windpipe (trachea).
  • Hyperthyroidism is when the thyroid gland is too active (overactive) and produces too much of a hormone called thyroxine.
  • The most common cause is Graves’ disease, a disorder in which your immune system attacks the thyroid gland.
  • Hyperthyroidism can cause various symptoms, such as unexplained weight loss, nervousness, inability to tolerate heat, or changes in your heartbeat.
  • Treatment may include medicine to reduce the amount of thyroid hormone your body makes, radioiodine therapy, surgery, or medicines to manage symptoms.

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