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.
Symptoms and Causes
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:
Diagnosis and Tests
How is thyroiditis diagnosed?
Tests for thyroiditis may include:
- Thyroid function tests measure the amounts of hormones (thyroid-stimulating hormone or TSH, T3, and T4) in the blood. TSH comes from the pituitary gland and stimulates the thyroid gland to produce T4 and T3. The thyroid gland produces the hormones T4 and T3 that exert the action of thyroid hormone in the body. T3 and T4 are called thyroid hormones.
- Thyroid antibody tests measure thyroid antibodies that include antithyroid (microsomal) antibodies (TPO) or thyroid receptor stimulating antibodies (TRAb).
- Erythrocyte sedimentation rate (ESR or sed rate) indicates inflammation by measuring how fast red blood cells fall. The ESR is high in sub-acute thyroiditis.
- Ultrasound (US), sonogram of the thyroid, is used very frequently to evaluate the anatomy of the thyroid gland. It can show a nodule (a growth) in the thyroid gland, a change in blood flow (Doppler mode) and echo texture (intensity/density) of the gland.
- Radioactive iodine uptake (RAIU) measures how much radioactive iodine is absorbed by the thyroid gland. The amount is always low in the thyrotoxic phase of thyroiditis.
Management and Treatment
How is thyroiditis treated?
How thyroiditis is treated depends on the type, symptoms, and phase of thyroiditis.
- Thyrotoxic phase: Usually temporary, it will eventually either recover and go to the euthyroid phase, or go to the hypothyroid phase. This hypothyroid phase could be temporary or permanent. It may not be necessary to treat symptoms in subacute, painless, or post-partum thyroiditis. During the thyrotoxic phase, treatment is symptomatic. Antithyroid medications are rarely needed.
- Palpitations/anxiety/tremors/heat intolerance/increased sweating: These symptoms are treated with beta blockers.
- Thyroidal pain: The pain can usually be managed with anti-inflammatory medications such as aspirin or ibuprofen. If the pain is severe enough, steroid therapy may be required (not very often).
- In other forms, treating the infection will be necessary to eliminate acute (suppurative) thyroiditis. Drug-induced thyroiditis generally lasts as long as the drugs are taken.
- Hypothyroid phase: If necessary, thyroid hormone replacement therapy is used to treat hypothyroidism. This type of therapy usually continues for 6 to 12 months. Hashimoto's thyroiditis usually causes permanent hypothyroidism and requires continued treatment.
Outlook / Prognosis
What is the outlook for a patient with thyroiditis?
In the case of Hashimoto's thyroiditis, the resulting hypothyroidism is generally permanent. People who develop subacute thyroiditis usually have symptoms for 1 to 3 months, but complete recovery of thyroid function can take up to 12 to 18 months. These people have about a 5 percent chance of developing a permanent condition of hypothyroidism.
The time frame for recovery to a thyroid that functions normally for post-partum, silent or painless thyroiditis is also about 12 to 18 months. People with these conditions have about a 20 percent chance of developing permanent hypothyroidism.