Subacute lymphocytic thyroiditis
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. [1][2] 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.[1]
Diagnosis
Subacute lymphocytic thyroiditis can only be diagnosed correctly by taking a radioactive iodine uptake test (RAIU) test.[1][3]
During the hyperthyroid phase, iodine uptake is suppressed, while during the hypothyroid phase, uptake is increased.[4]
This situation contrasts greatly with the elevated iodine uptake found in patients with Graves' disease.[1]
Treatment
Treatment is based on symptoms. Beta-blockers relieve rapid heart rate and excessive sweating during the hyperthyroid phase.[4]