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Hypothyroidism - What it is

The thyroid gland is a butterfly-shaped gland in the middle of the neck. It produces thyroid hormones, which are important for maintaining our body’s metabolism. 

Hypothyroidism means that the thyroid gland is underactive, and is not producing enough thyroid hormone. This may cause a “slowing down” of many bodily functions.

Hypothyroidism - Symptoms

Symptoms of hypothyroidism may include the following:
  • Cold intolerance (you feel cold more easily compared to other people)
  • Weight gain
  • Fatigue and weakness
  • Constipation
  • Abnormal menses or heavy / prolonged menses
  • Depression or irritability
  • Hair loss
  • Dry, rough skin
  • Muscle aches or cramps
Occasionally, some patients with hypothyroidism have no symptoms, or symptoms that are subtle enough to go unnoticed.

Hypothyroidism - How to prevent?

​There is no known way to prevent hypothyroidism.

Hypothyroidism - Causes and Risk Factors

There are many reasons why hypothyroidism occurs. The more common causes include the following:
  • Hashimoto’s disease
    This is the most common cause of hypothyroidism. It is an “autoimmune”, or “self-attacking-self” disease. It occurs when the body’s immune system mistakenly attacks thyroid cells and damages them. Over time, the thyroid gland fails, causing hypothyroidism.
  • Radioactive iodine treatment
    Hypothyroidism often develops as a desired treatment goal after the use of radioactive iodine treatment for high thyroid hormone production (hyperthyroidism).
  • Thyroid operation
    Previous thyroid surgery can cause hypothyroidism, especially if most of the thyroid gland has been removed.
  • Medication
    Some medication including amiodarone and lithium can cause hypothyroidism
  • Subacute thyroiditis
    This causes a painful inflammation of the thyroid. This causes a period of hyperthyroidism (high thyroid hormone level) as the damaged cells leak their hormone supply into the bloodstream, but this is followed by a period of hypothyroidism.
  • Congenital hypothyroidism
    A baby may be born with an insufficient amount of thyroid tissue or a problem that does not allow normal thyroid hormone production
Less commonly, hypothyroidism can also be caused by problems in the pituitary gland, the “master hormone gland” that controls the thyroid gland.

Hypothyroidism - Diagnosis

Hypothyroidism can be diagnosed with blood tests which measure the amount of thyroid hormone. 
T4 (the main thyroid hormone that is produced by the thyroid gland) is expected to be low in hypothyroidism. 
TSH (thyroid-stimulating hormone) is a hormone produced by the pituitary gland. The pituitary gland is the master hormone gland that controls the thyroid gland. Both the T4 and TSH hormones are usually tested together.

Hypothyroidism - Treatments

Hypothyroidism is treated with thyroxine replacement. This boosts the amount of thyroid hormone in the bloodstream back to normal levels. It is given as a small pill daily. It has very few side effects and almost no allergic reactions. The correct dose is determined with the help of blood tests (including both T4 and TSH levels). 

Hypothyroidism - Preparing for surgery

Hypothyroidism - Post-surgery care

Hypothyroidism - Other Information

The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth