What is Thyroiditis?
Thyroiditis is the term for inflammation of the thyroid gland, the bilobular gland located just below the voice box (larynx). The thyroid gland has several functions in the body but is best known for regulating the metabolism through the action of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Thyroiditis includes several diseases of the thyroid gland with varying presentation and etiology – from infections to autoimmune disorders and drugs.
Although inflammation is almost always associated with pain, there are forms of thyroiditis where pain is absent and other features of inflammation are minimal. Some of these disorders are characterized primarily by the effect of abnormal levels of thyroid hormones. Thyroiditis may be acute, subacute or chronic – most acute and subacute types of thyroiditis are due to infections, while chronic thyroiditis is usually due to autoimmune factors.
Thyroiditis may lead to either an excess or deficiency of thyroid hormones. Some types of thyroiditis can be treated thereby restoring normal thyroid functioning. However in those types of thyroiditis where treatment cannot restore normal thyroid activity, synthetic thyroid hormones or antithyroid medication is used to counteract the effects of thyroid dysfunction.
Types of Thyroiditis
- Acute thyroiditis is due to infections and often referred to as infectious thyroiditis. It can be caused by any pathogen but most cases are due to bacterial infections. Acute infectious thyroiditis usually does not result in thyroid dysfunction although mild hypothyroidism may be present at times. However this will resolve once the infection settles or is treated appropriately.
- Subacute granulomatous thyroiditis, also known as de Quervain’s thyroiditis, may possibly be triggered by a viral infection. Subacute lymphocytic thyroiditis (painless thyroiditis) is linked to autoimmune causes and is similar to post partum thyroiditis. All these types of thyroiditis are characterized by hyperthyroidism (thyrotoxicosis) followed by hypothyroidism and usually lasts for 12 to 18 months. Collectively, there types of thyroiditis are known as subacute thyroiditis.
- Hashimoto’s thyroiditis is a chronic type of thyroiditis that is due to autoimmune factors. The pathogenesis is closely related to subacute lymphocytic (painless) thyroiditis and post partum thyroiditis. It is characterized by hypothyroidism with thyrotoxicosis rarely seen in the initial stages of the disease.
- Drug-induced thyroiditis and radiation thyroiditis arise as a result of therapeutic measures like the use of lithium or chemotherapeutic agents, radioactive iodine or radiation therapy. With drug-induced thyroiditis, the thyroid dysfunction (either thyrotoxicosis or hypothyroidism) usually wears off after stopping the drug. In radiation thyroiditis, however, the hypothyroidism that may follow the initial hyperthyroidism is usually permanent.
- Reidel’s thyroiditis or fibrous thyroiditis is rare type of chronic thyroiditis that results in the growth of fibrous tissue in the thyroid gland. The cause of Reidel’s thyroiditis is unknown but is possibly due to autoimmune factors.
Inflammation of the thyroid gland is known as thyroiditis. It may occur due to an infection, autoimmune disorders or may be a result of therapeutic measures like the use of certain drugs or radiation therapy. There are various types of thyroiditis but the signs and symptoms are marked by either an overactivity or underactivity of the thyroid gland leading to an excess or deficiency of thyroid hormones respectively. Pain may or may not be present in these different types of thyroiditis.
Thyroiditis Signs and Symptoms
Hyperthyroidism is the overactivity of the thyroid gland leading to an excess of thyroid hormones. The high levels of thyroid hormones (thyrotoxicosis) may result in the following signs and symptoms :
- Weight loss
- Anxiety and irritability
- Rapid heart rate (tachycardia)
Hypothyroidism is the underactivity of the thyroid gland leading to a deficiency of thyroid hormones (low levels). The following signs and symptoms may be seen :
- Weight gain
- Intolerance to cold
- Dry skin
- Thinning hair
Painful and Painless Thyroiditis
Thyroid pain is characterized by pain, tenderness or discomfort on the neck, slightly lateral to the midline. It extends from just below the Adam’s apple to the upper part of sternum (breastbone).
A painful thyroid gland may be reported with :
- acute thyroiditis (infections) – usually no prominent signs of hypothyroidism or thyrotoxicosis
- subacute granulomatous thyroiditis (de Quervain’s thyroiditis) – initially thyrotoxicosis followed by hypothyroidism
Painless thyroiditis is seen with :
- subacute lymphocytic thyroiditis – thyrotoxicosis which may be followed by hypothyroidism
- post-partum thyroiditis – thyrotoxicosis which may be followed by hypothyroidism
- Hashimoto’s thyroiditis – hypothyroidism although there may be a transient thyrotoxicosis at the outset