Abstract

Subacute lymphocytic thyroiditis is a form of thyroiditis that is also known as silent thyroiditis or painless thyroiditis. Subacute lymphocytic thyroiditis may occur at any age and is more common in females.

A variant of subacute lymphocytic thyroiditis occurs postpartum, postpartum thyroiditis. Both of these entities can be considered subtypes of Hashimoto's thyroiditis and have an autoimmune basis. Anti-thyroid antibodies are common in all three and the underlying histology is similar. This disorder should not be confused with de Quervain's thyroiditis which is another form of subacute thyroiditis.

Symptoms

Subacute lymphocytic thyroiditis features a small goiter without tenderness. This condition tends to have a phase of hyperthyroidism followed by a return to a euthyroid state, and then a phase of hypothyroidism, followed again by a return to the euthyroid state. The time span of each phase can vary; however, each phase usually lasts 2–3 months.

Diagnosis

Subacute lymphocytic thyroiditis can only be diagnosed correctly by taking a radioactive iodine uptake test (RAIU) test.

During the hyperthyroid phase, iodine uptake is increased, while during the hypothyroid phase, uptake is decreased.

This situation contrasts greatly with the elevated iodine uptake found in patients with Graves' disease.

Treatment

Treatment is based on symptoms. Beta-blockers relieve rapid heart rate and excessive sweating during the hyperthyroid phase.