What is thyroiditis?
The thyroid gland is a butterfly-shaped gland (weighing about 15-20 grams) located in the front of the lower neck between the Adam's apple and the breastbone. The thyroid makes hormones that control metabolism. Metabolism is the pace at which your body processes things (how fast it burns food to make energy and heat).
Thyroiditis is the swelling, or inflammation, of the thyroid gland and can lead to over- or under-production of thyroid hormone. There are three phases to thyroiditis:
- Thyrotoxic phase. Thyrotoxicosis means that the thyroid is inflamed and releases too many hormones.
- Hypothyroid phase. Following the excessive release of thyroid hormones for a few weeks or months, the thyroid will not have enough thyroid hormones to release. This leads to a lack of thyroid hormones or hypothyroidism.
- Euthyroid phase. During the third euthyroid phase, the thyroid hormone levels are normal. This phase may come temporarily after the thyrotoxic phase before going to the hypothyroid phase, or it may come at the end after the thyroid gland has recovered from the inflammation and is able to maintain a normal hormone level.
What are the types of thyroiditis?
- Hashimoto’s thyroiditis: an autoimmune condition caused by anti-thyroid antibodies. This is the most common form of thyroiditis and is around five times more common in women than in men. Hashimoto’s thyroiditis usually results in hypothyroidism, and thyroid hormone replacement treatment is needed.
- Silent thyroiditis or painless thyroiditis: another autoimmune disease caused by anti-thyroid antibodies. It is also common in women and the next common cause after Hashimoto’s thyroiditis.
- Post-partum thyroiditis: an autoimmune condition caused by anti-thyroid antibodies that sometimes occurs shortly after a woman gives birth
- Radiation-induced thyroiditis: a condition caused by external radiation used as a medical treatment for certain cancers, or by radioactive iodine used to treat hyperthyroidism
- Subacute thyroiditis or de Quervain’s thyroiditis: an often painful condition thought to be caused by a virus
- Acute thyroiditis or suppurative thyroiditis: a relatively rare condition caused by an infectious organism or bacterium
- Drug-induced thyroiditis: a condition is caused by the use of drugs such as amiodarone, interferons, lithium, and cytokines. It only occurs in a small fraction of patients using the offending drugs, so it is not common in the normal population.
What causes thyroiditis?
The thyroid can be attacked by different agents. The attacks cause inflammation and injury to the thyroid cells, leading to thyroiditis.
Some of the agents known to cause thyroiditis are antibodies (the most common cause), drugs, radiation and organisms (viruses and bacteria). Conditions in which the body attacks itself are autoimmune diseases. Thyroiditis can be an autoimmune disease (antibody-mediated).
It is not certain why some people make thyroid antibodies. Thyroid disease is known to run in families. Thyroiditis can be caused by an infection or can be a side effect of certain drugs.
What are the symptoms of thyroiditis?
The symptoms of thyroiditis depend on the type of thyroiditis and phase of thyroiditis.
- Hyperthyroid phase: Usually short lasting (1-3 months.) If cells are damaged quickly and there is a leak of excess thyroid hormone, you might show symptoms of hyperthyroidism, such as:
- Hypothyroid phase (more common): Can be long-lasting and may become permanent. If cells are damaged and thyroid hormone levels fall, you might show symptoms of hypothyroidism, such as: