Causes of Thyroiditis
Thyroiditis is the inflammation of the thyroid and is caused by antibodies attacking the thyroid due to an autoimmune disease. The inflammation can be temporary or chronic depending on the underlying process.
This problem can occur in the following situations:
Due to a viral infection.
Due to a bacterial infection.
Because of certain drugs (amiodarone, lithium, immunotherapy) that accumulate in the thyroid or affect the immune system, as well as external irradiation that can also induce thyroid inflammation.
Its origin is very diverse and involves immunological, genetic, infectious and environmental factors. As a result, thyroiditis is difficult to classify using a single approach. It can be divided according to its origin, symptoms and pathology.
The presence or absence of pain is one of the most practical classifications:
Subacute thyroiditis (granulomatous or DeQuervain's). This is associated with a viral illness about 2-8 weeks prior to the onset of symptoms. Autoimmunity does not seem to play a role, but some patients may have positive autoimmunity.
Infectious thyroiditis. Pain usually appears abruptly due to the formation of an abscess. It is caused by germs reaching the thyroid via the blood or via a fistula from the respiratory tract. The organisms that most frequently cause this are Staphylococcus aureus, Streptococcus, E. coli and Salmonella.
Radiation thyroiditis. This may occasionally occur after iodine treatment in patients with hyperthyroidism.
Trauma-induced thyroiditis. This occurs during cervical surgery or after trauma to the area.
Silent thyroiditis. This is considered a variant of chronic autoimmune thyroiditis. It usually presents with high levels of anti-TPO and anti-TG antibodies, and is often associated with a long family history of autoimmune thyroid disease.
Postpartum thyroiditis. This occurs in women up to 12 months after childbirth or miscarriage. It is seen in 5-9% of pregnancies. It is associated with the presence of anti-TPO and anti-TG antibodies. It reflects the immune suppression that takes place during pregnancy, followed by rebound of the immune system in the postpartum period.
Medication-induced thyroiditis. Amiodarone, lithium, immunomodulatory drugs (e.g., etanercept, interferon, interleukin-2, cancer immunotherapy), and tyrosine kinase inhibitors can cause thyroiditis.
Fibrous (Riedel's) thyroiditis. Its origin is unclear, but it is thought to be a local manifestation of a systemic disease known as idiopathic multifocal fibrosclerosis.