What Is Thyroiditis?

Thyroiditis is any infection or inflammation involving the thyroid gland.  It can be due to a virus, a bacteria or autoimmunity, the attempt by the body to damage its own thyroid.  In this article, I will tell you about the common forms of thyroiditis and what you and your doctor can do about them.

Chronic Thyroiditis

The most common form of thyroiditis by far is chronic thyroiditis, also known as autoimmune thyroiditis or Hashimoto’s thyroiditis.  Chronic thyroiditis is hereditary, usually being passed down from mother to daughter, but sometimes to sons as well.  In chronic thyroiditis, the body mistakes the thyroid gland as a foreign invader and produces antibodies (proteins against cells or tissues) that prevent the thyroid gland from working normally.  The result is usually low thyroid function known as hypothyroidism. It must be treated with thyroid hormone replacement.  Chronic thyroiditis is the main cause of hypothyroidism.  The thyroid gland is often enlarged but it is not tender.

Subacute Thyroiditis

Subacute thyroiditis is believed to start as a viral infection in the body that spreads to the thyroid gland.  The course of thyroiditis is divided into 4 stages.

  • Stage 1: the thyroid is tender and painful.  A blood test called the erythrocyte sedimentation rate (ESR) is very elevated, indicating that there is much inflammation.  The patient also has muscle aches and pains.  In this stage the thyroid is damaged by the virus and releases all the stored thyroid hormone and thyroid hormone tests show high levels of free thyroxine, the active form of thyroid hormone.  The condition could be mistaken for hyperthyroidism, but hyperthyroidism is not usually painful.  The high levels of thyroid hormone are also temporary so no treatment is given to decrease production of thyroid hormone as would be done for hyperthyroidism.  This stage may last a few days.
  • Stage 2:  this stage lasts a few weeks during which you experience normal thyroid function as the thyroid levels fall and are not replaced.  The inflammation in the thyroid begins to subside and it becomes less tender.
  • Stage 3 may last a month or more.  The patient is hypothyroid (has low thyroid function) as the free thyroxine falls and is not replaced by the damaged thyroid gland.
  • Stage 4 is gradual return to normal as the viral illness subsides and the thyroid begins to function normally again.  There is usually no long term damage due to subacute thyroiditis.  The patient fully recovers, but occasionally becomes permanently hypothyroid after a time in 5 percent of cases

Subacute thyroiditis is 3 times more common in women than men.  .  It occurs most often when a patient is 40 or 50 years of age.  It may recur years later in some patients.

Treatment is with drugs to reduce the hyper symptoms at first as well as aspirin to reduce inflammation.  If the low thyroid function persists later, thyroid hormone replacement is given.

Postpartum Thyroiditis and Silent Thyroiditis

5 to 10 percent of pregnancies are complicated by postpartum thyroiditis.  It is considered to be an autoimmune disease because high levels of thyroid autoantibodies are found in the blood.  Postpartum thyroiditis is like subacute thyroiditis but the thyroid gland is not hot or painful and the patient has no symptoms of a viral illness.  The patient goes through the following stages:

  • Stage 1 beginning a month after delivery and lasting up to 3 months, the patient has signs and symptoms of hyperthyroidism
  • Stage 2 is the stage of normal thyroid function for a month or two
  • Stage 3 is the stage of hypothyroidism at 4 to 6 months after delivery
  • Stage 4 is resolution of the hypothyroidism, but the patient is at high risk of permanent hypothyroidism after 3 to 5 years.  As many of 50 percent or women with this condition will be permanently hypothyroid.

The woman who has postpartum thyroiditis will probably have it after each pregnancy.  In postpartum thyroiditis, the erythrocyte sedimentation rate is normal.

Silent thyroiditis is similar to postpartum thyroiditis but there is no prior pregnancy and it occurs in men as well as women.  Otherwise the course is the same and it has the same rate of permanent hypothyroidism.

Acute Thyroiditis

Acute thyroiditis is a rare and severe acute illness due to bacterial infection of the thyroid gland.  The thyroid gland is large and extremely tender.  The patient has high fever and structures near the thyroid such as the esophagus and the trachea are inflamed as well.  This may result in trouble swallowing or breathing.

If a needle is inserted into the thyroid, pus is usually found.  It may contain one of several bacteria.  Treatment is with an antibiotic directed at that bacteria.  Other medications such as aspirin for fever are also given.  If the infection does not respond to treatment, it may be necessary to remove the affected part of the gland with surgery.

The thyroid function usually remains normal during acute thyroiditis, but sometimes so much damage is done to the thyroid that a great deal of thyroid hormone leaks out and there is temporary hyperthyroidism.

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