What Is Hypothyroidism?

The thyroid is an endocrine gland located in your neck that regulates energy levels, creates proteins, and determines how the body should respond to all of the hormones in the system.

Hypothyroidism (or an under-active thyroid) occurs when an individual's thyroid does not produce enough of the thyroid hormone that controls these systems. People with hypothyroidism may need to take medication to help regulate their thyroid hormone levels.

Other areas of the body that help the thyroid regulate your hormones and metabolism can malfunction and cause hypothyroidism, as well:

  • The pituitary gland creates Thyroid-Stimulating Hormone (TSH), and if it does not produce enough, the thyroid will not get the message to produce hormones for the body.

  • The hypothalamus controls the pituitary gland's creation of TSH by releasing TRH and disturbances within that system will affect the thyroid gland.


Causes of Hypothyroidism:

There are several conditions that can cause hypothyroidism.

The most common cause for hypothyroidism is an autoimmune disorder called Hashimoto's Thyroiditis, also known as chronic lymphocytic thyroiditis or autoimmune thyroiditis, which causes the body’s immune system to attack the thyroid gland. White blood cells, or leukocytes, accumulate in the thyroid causing chronic inflammation and cell damage, making it difficult for the thyroid to function properly.

Hashimoto’s Thyroiditis tends to run in families, and is more common in women than men. In addition to the symptoms of hypothyroidism outlined below, patients with Hashimoto’s Thyroiditis may also experience a feeling of fullness in the throat (from the enlarged gland), develop goiters, gain weight, and have a slowed heart rate. Treatment is not always required for Hashimoto’s Thyroiditis, but if warranted, a synthetic thyroid hormone will be prescribed.

When a part of the thyroid gland is removed - which may occur in cancer treatment - it causes hypothyroidism as the remaining portion of the thyroid cannot keep up with the body's demand for hormones due to its reduced cellular volume.

Some individuals who have undergone radioactive iodine therapy - which may occur during treatment for hyperthyroidism - may experience thyroid damage and develop hypothyroidism.

Some drugs and certain viruses can also cause hypothyroidism.

Who Gets Hypothyroidism?

Anyone can get hypothyroidism, but women - especially older women - are more likely than men to development the condition. There's also a genetic component in thyroid disorders as thyroid disease runs in families.

1 in every 4,000 babies is born with a malfunctioning thyroid gland. This is called congenital hypothyroidism. Babies are usually checked at birth for it.

If you have diabetes, vitiligo, pernicious anemia, or premature gray hair, you may have a higher risk of hypothyroidism.

Symptoms of Hypothyroidism:

  • Fatigue
  • Menstrual problems
  • Increased sensitivity to cold
  • Depressed mood or excessive irritability
  • Muscle cramps and joint pain
  • Brittle fingernails
  • Coarse hair and/or dry, itchy skin
  • Decreased sex drive
  • Constipation
  • Memory problems
  • Goiters (a secondary condition to high levels of TSH)

This list is by no means all-inclusive or meant to diagnose hypothyroidism. If you suspect you may have hypothyroidism, call your doctor.

In rare cases which hypothyroidism is left untreated, severe depression, heart failure, or coma may result.

Diagnosis of Hypothyroidism:

Physicians will administer a simple blood test to diagnose hypothyroidism.

A doctor will check the levels of different hormones in your blood; these are called TSH, T3 and T4.

If the level of TSH (thyroid stimulating hormone) in the blood is high, this indicates that the body is making more TSH than necessary to get the thyroid to behave properly.

When abnormalities are found in the levels of these hormones, individuals may be referred to an endocrinologist for further testing to determine if the pituitary gland and/or hypothalamus are contributing to the problem.

Mild cases of hypothyroidism may be left undiagnosed because the hormone levels are still within the normal realm, such as in early cases of the disease.

In addition, sometimes the normal range of thyroid hormones for an individual may differ from the clinical standards; this is why it is important to seek the advice of an endocrinologist if hypothyroidism is suspected.

Treatment for Hypothyroidism:

Those with hypothyroidism are usually given a synthetic form of the thyroid hormone in the form of a pill. The individual type of synthetic hormone prescribed will depend on TSH levels, as well as the exact type of hypothyroidism.

If the patient's hypothyroidism is a result of a pituitary malfunction, medication or surgery (in the case of a pituitary tumor) may be warranted.

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Additional Resources:

The American Thyroid Association provides medical news and information for thyroid-related issues. They also operate a hotline: 1-800-THYROID.

The Hormone Foundation has resources for patients and professionals looking for additional information on hormone-related issues, and runs the hotline 1-800-HORMONE.

The Endocrine Society provides news and advocacy information for all endocrine disorders.

The American Association of Clinical Endocrinologists' website can help you find an endocrinologist in your area.