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Hypothyroidism: Overview, Causes, Symptoms, Treatments and More | Singapore General Hospital

Hypothyroidism - What it is

The thyroid is a butterfly-shaped gland situated in the front of the neck. Its main function is to produce two hormones - thyroxine and triiodothyronine - which are crucial to the control of various bodily functions.

Should the thyroid malfunction, it can cause health problems that can affect your quality of life. Women are more susceptible than men to thyroid disorders. Thyroid hormone (TH) imbalances are usually related to autoimmune disorders - when healthy cells and tissues in your body are mistakenly attacked by your own immune system. It is not known why this happens, but there appears to be a genetic link.

Too little, too much?

When an underactive gland doesn't produce enough thyroid hormones to adequately meet the body's needs, the condition is referred to as hypothyroidism. Conversely, in hyperthyroidism; an overactive thyroid gland results in the excessive production of thyroid hormones. Hypothyroidism and hyperthyroidism are the two most common thyroid disorders in women between the age of 20 and 50, who are also five times more likely than men to develop thyroid disorders.


Left untreated, hypothyroidism may cause complications such as:

  • Increased risk of developing heart disease. A low thyroxine level causes blood lipids such as LDL, or "bad" cholesterol, to rise.
  • Increased risk of developing pregnancy complications. Examples include pre-eclampsia, anaemia, premature labour, low birth weight, stillbirth, birth defects, and serious bleeding after childbirth.
  • Myxedema coma. A very rare complication that may be fatal.

Hypothyroidism - Symptoms

The signs and symptoms of hypothyroidism vary widely, depending on the severity of the hormone deficiency, but these tend to develop slowly, often over a number of years. You may barely notice symptoms such as fatigue and sluggishness, which may seem to be just part and parcel of getting older at first. As your metabolism continues to slow, the signs and symptoms become more obvious.

  • Fatigue
  • Sluggishness
  • Increased sensitivity to the cold
  • Constipation
  • Pale, dry skin
  • Puffy face
  • Hoarseness of voice
  • Unexplained weight gain
  • Muscle weakness, aches, tenderness and stiffness
  • Joint pain, stiffness or swelling
  • Light or irregular periods
  • Brittle fingernails and hair
  • Depression
  • Forgetfulness

Hypothyroidism - How to prevent?

Hypothyroidism - Causes and Risk Factors

There are several causes of hypothyroidism, including autoimmune disease, treatment for hyperthyroidism, radiation therapy, thyroid surgery and certain medications. The most common cause is an autoimmune disorder called Hashimoto's disease.

Hypothyroidism - Diagnosis

Hypothyroidism - Treatments

Hypothyroidism is treated with hormone replacement, using a synthetic thyroid hormone pill (thyroxine) that aims to regulate thyroid hormone levels and normalise your metabolism. Do note that there may be some trial and error before arriving at the right dose. Your doctor will typically start you on a low dose, to be increased as necessary, if the symptoms persist or blood tests still show abnormal levels. You will be put on medication for life, and have to see your doctor regularly to check your thyroid stimulating hormone (TSH) levels, to ensure that the treatment is not causing hyperthyroidism.

Hypothyroidism - Preparing for surgery

Hypothyroidism - Post-surgery care

Hypothyroidism - Other Information

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