Subacute thyroiditis

Subacute thyroiditis refers to a temporal classification of the different forms of thyroiditis based on onset of symptoms. The temporal classification of thyroiditis includes presentation of symptoms in an acute, subacute, or chronic manner. There are also other classification systems for thyroiditis based on factors such as clinical symptoms and underlying etiology.

Broadly, there are three categories of thyroiditis that can present in a subacute fashion, including subacute granulomatous thyroiditis, subacute lymphocytic thyroiditis, and drug-induced thyroiditis. In all three categories, there is inflammation of the thyroid gland causing damage to the thyroid follicular cells which produce and secrete thyroid hormone. This often results in three phases of thyroid dysfunction beginning with initial thyrotoxicosis followed by hypothyroidism before resolution back to normal thyroid function. In the thyrotoxic stage, individuals usually complain of fever, myalgia, and may have associated anterior neck pain among other symptoms. In the hypothyroid stage, they may be asymptomatic or experience mild symptoms. In most cases, the thyroid dysfunction is transient and people recover with symptomatic treatment.