Subacute thyroiditis is a self-limited thyroid condition associated with a triphasic clinical course of hyperthyroidism, hypothyroidism, and return to normal thyroid function. Subacute thyroiditis may be responsible for 15-20% of patients presenting with thyrotoxicosis and 10% of patients presenting withhypothyroidism. Recognizing this condition is important, because it is self-limiting, and no specific therapy, such as antithyroid or thyroid hormone replacement therapy, is necessary in most patients.
Thyroiditis refers to inflammation of the thyroid gland. Subacute thyroiditis (SAT) is a self-limited condition characterized by a triphasic course ofhyperthyroidism followed by hypothyroidism and ending with euthyroidism. Subacute thyroiditis may account for 15-20% of thyrotoxicosis presentations and 10% of hypothyroidism presentations. The thyrotoxicosis results from release of preformed thyroid hormone. This phase lasts 4-10 weeks. The disease undergoes remission in 2-4 months. At this time, the thyroid is depleted of colloid and is now incapable of producing thyroid hormone, resulting in hypothyroidism. The hypothyroidism may be mild and not requiring any therapy. As the follicles regenerate, the euthyroid state is restored. Up to 95% of patients return to this normal thyroid state.
Subacute thyroiditis (subacute granulomatous thyroiditis) is characterized by neck pain or discomfort, a tender diffuse goiter, and a predictable course of thyroid function evolution. Hyperthyroidism is typically the presentation followed by euthyroidism, hypothyroidism, and ultimately restoration of normal thyroid function (figure 1). The diagnosis and management of subacute thyroiditis will be provided here.