Thyroiditis is a group of disorders involving swelling of the thyroid gland. Inflammation of the thyroid leads to an over- or under-production of thyroid hormones, which can have a wide range of effects on the body. Additionally, there are many types of thyroiditis and each condition typically progresses through several phases. Each type has unique symptoms, causes, and treatments.
The thyroid is a butterfly-shaped gland that sits just above the breastbone. It creates hormones and secretes them into the bloodstream, which carries them to every tissue in the body. These hormones control metabolism. Thyroid hormones play a key role in many vital functions including heart rate, how fast the body burns calories, and heat production. They are also involved in skin, reproductive, and digestive health.
Thyroiditis can result from any attack on the thyroid that causes inflammation or injury. The most common offenders include medications, radiation, viruses, and bacteria. Autoimmune forms are common, but it is unclear why some people’s bodies produce anti-thyroid antibodies. Autoimmune thyroiditis often runs in families, making it possible to predict who has a higher risk of developing the condition.
Many cases of thyroiditis progress through three phases. The thyrotoxic phase is when thyroid becomes inflamed and releases excess hormones. While this is similar to hyperthyroidism, the gland is not truly overactive in this phase. After a period of releasing too many hormones, the thyroid enters the hypothyroid phase. In this phase, the gland does not have enough hormones to release, causing hypothyroidism. The third and final phase is the euthyroid phase, where hormones return to their typical levels. This phase can be temporary or permanent.
Many types of thyroiditis exist, but the most common are autoimmune diseases resulting from anti-thyroid antibodies. Hashimoto’s thyroiditis is the most common and usually results in hypothyroidism. Silent or painless thyroiditis is the second most prevalent form. Some females develop postpartum thyroiditis shortly after giving birth. These latter two are similar in presentation and often temporary.
Non-autoimmune forms of thyroiditis also exist. Radiation-induced thyroiditis stems from external radiation, such as medical treatments for cancer. Acute or suppurative thyroiditis is a rare type that results from an infectious organism or bacteria. Similarly, a viral infection may cause subacute or de Quervain’s thyroiditis. Certain medications may trigger drug-induced thyroiditis.
Thyroiditis has no symptoms unique to itself. Instead, symptoms vary depending on the levels of hormones and the specific condition. Typical symptoms of the high thyroid hormone levels include anxiety, insomnia, fatigue, irritability, unexpected weight loss, and palpitations. Thyrotoxicosis and hyperthyroidism share similar symptoms because are both caused by increased levels of thyroid hormone in the blood. However, in thyrotoxicosis, the thyroid is not truly overactive. Postpartum and silent thyroiditis usually begin in the thyrotoxic phase before progressing. Symptoms of thyrotoxicosis usually only last for a few months.
Low levels of thyroid hormones can also cause many issues. Common symptoms of hypothyroidism include fatigue, unexpected weight gain, dry skin, poor exercise tolerance, constipation, and depression. These symptoms are typical of Hashimoto’s thyroiditis and the later stages of postpartum and silent thyroiditis. Symptoms of hypothyroidism can be long-lasting if left untreated.
Doctors use a range of tests to determine thyroid function and detect conditions like thyroiditis. Thyroid function tests measure the thyroid hormone levels in the blood. Thyroid antibody tests measure thyroid and anti-thyroid antibodies. Imaging tests such as ultrasounds, radioactive iodine uptake tests, and thyroid scans may also be helpful.
Management and treatment of thyroiditis are dependent on the type, phase, and current symptoms. Because the thyrotoxic phase is temporary, treatment targets the symptoms instead, though people with subacute, silent, or postpartum thyroiditis may not need it.
Beta-blockers treat palpitations, anxiety, and tremors. Anti-inflammatory drugs can help manage thyroidal pain. Thyroid hormone replacement therapy is necessary for hypothyroidism, such as Hashimoto’s thyroiditis.
Like treatment options, the prognosis also depends on the specific condition. Some forms, such as silent, subacute, or postpartum thyroiditis, tend to be temporary. In Hashimoto’s thyroiditis, hypothyroidism is often a chronic, long-term condition requiring continual treatment. People with temporary forms of thyroiditis should expect to recover over 12 to 18 months.
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