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Hypothyroidism

Introduction

  • Hypothyroidism is a condition due to underactive thyroid gland. There is a decrease in the production of thyroid hormones which slows down the body functions.
  • More than 15% of older people have some degree of hypothyroidism. Women are affected about twice as often as men.

Causes

  • In many people, a specific cause cannot be found
  • Hashimoto’s thyroiditis (the most common specific cause of hypothyroidism) – the thyroid gland may enlarge initially but as the disease progresses, it will damage the thyroid gland resulting in hypothyroidism.
  • Drugs eg. those used to treat overactivity of the thyroid gland, lithium (used to treat mental illness) and amiodarone (used to treat heart disease)
  • Previous surgical removal of the thyroid gland
  • Previous thyroid radiation
  • Disorders of the hypothalamus or pituitary gland (these are rare causes).

Sign and Symptoms

Elderly patients have significantly fewer symptoms of hypothyroidism than their younger adults and complaints are often subtle and vague.

Symptoms of hypothyroidism:

  • Sensitivity to cold
  • Constipation
  • Weight gain
  • Feeling tired
  • Dry and coarse skin, puffy face and swelling especially around the eyes.
  • Depressed mood
  • Muscles and joints may be painful or weak, which can interfere with the ability to walk.
  • Non-specific symptoms eg. confusion, loss of appetite, weight loss, falling, incontinence, and decreased mobility
  • Coma (or lost of consciousness) if severe and can be fatal

The term subclinical hypothyroidism implies that the patient has no symptoms of hypothyroidism and it can only be diagnosed by blood tests.

Diagnosis

  • Thyroid gland may be enlarged
  • Body temperature may be slightly decreased
  • Some evidence of hypothyroidism eg. puffy eyes, dry skin etc
  • By tapping the knees, ankles, and elbows, the reflexes may be slow
  • However, the examination findings may be normal in some cases.

Blood tests

  • Level of thyroid-stimulating hormone (TSH) – above normal (usually > 4.5 mU/L) suggests a possible diagnosis of hypothyroidism.
  • Level of free T4 hormone – should be measured to differentiate overt hypothyroidism (low free T4) from subclinical hypothyroidism (normal free T4).
  • Other tests may be needed to determine the cause.

Screening

  • For those with risk factors for thyroid disease, the serum TSH level should be checked more often.
  • Screening for hypothyroidism is cost-effective – it is highly sensitive and specific in diagnosing or excluding two prevalent and serious disorders (hypothyroidism and hyperthyroidism), both of which can be treated effectively.
  • It should also be done in people with high cholesterol levels, which can be caused by an underactive thyroid gland.

Complications of hypothyroidism include:

  • High blood pressure
  • High cholesterol level and risk factor for heart disease
  • Heart Attack and heart failure are serious but uncommon
  • Coma (myxedema coma) is life-threatening emergency  with mental confusion which progresses to coma

Treatments

  • Elderly with hypothyroidism need to take thyroid hormone to replace the hormones that the thyroid gland is no longer producing
  • Treatment usually begins with a small dose and slowly increased about every 4 weeks.
  • People who have heart disease or other serious disorders should begin treatment with a smaller dose, which is increased even more slowly to reduce the risk of side effects from treatment.
  • After about 3 to 4 months, the dose occasionally needs to be adjusted, depending on weight loss or gain and the use of certain drugs.
  • To help determine if the elderly is responding well to treatment, the level of TSH has to be measured periodically
  • Treatment is very successful in eliminating or reducing the symptoms of hypothyroidism

Treatment with thyroid hormone almost always has to be continued for life because treatment does not cure the hypothyroidism.

Last Review : 26 April 2012
Writer : Dr. Ho Bee Kiau
Reviewed : Dr. Ho Bee Kiau