Hypothyroidism happens when the thyroid gland does not produce enough thyroid hormone. The thyroid gland is a butterfly-shaped gland in the front of the neck. It produces hormones that control metabolism. The most common form is Hashimoto's thyroiditis.

Thyroid Gland

thyroid gland male
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Hashimoto's thyroiditis occurs when:

  • Immune system produces antibodies that attack cells of the thyroid gland, causing chronic thyroid swelling and loss of function
  • Other causes:
    • Idiopathic thyroid atrophy—destruction of thyroid tissue for unknown reasons
    • Iodine deficiency—when a thyroid gland needs iodine to produce thyroid hormone (rare in the US)
    • Subacute thyroiditis—following a viral upper respiratory tract infection
    • Medical treatments— radiation to the head and neck or surgical removal of part of the thyroid gland (called subtotal thyroidectomy )
    • Medications (eg, lithium , iodine, alpha-interferons, thiourea, amiodarone , interleukins)
    • Certain diseases (eg, cancer or infection)
    • Pituitary adenoma —benign tumor of the pituitary gland

Risk Factors

These factors increase your chance of developing hypothyroidism:

Risk factors include:

Tell your doctor if you have any of these risk factors.


Years may pass before you notice symptoms.

Symptoms include:

Symptoms of severe or prolonged cases include:

  • Stupor or coma
  • Slow heart rate
  • Depressed breathing
  • Hypothermia (low body temperature)
  • Hoarseness


The doctor will ask about your symptoms and medical and family history, and perform a physical exam. To confirm the diagnosis, blood tests will be done, which include:

  • Thyroid stimulating hormone (TSH)
  • Free T4 and free T3
  • Antibodies that attack the thyroid gland


In the early stages of Hashimoto's thyroiditis, there is no specific treatment. But, in most cases, you will end up developing hypothyroidism. Treatment includes:


To help reduce your chance of getting hypothyroidism, take the following steps: