Subacute granulomatous thyroiditis

Last reviewed: March 2019

Last updated: March 2018

Summary

Inflammation of the thyroid characterised by a triphasic course of transient thyrotoxicosis, followed by hypothyroidism, followed by a return to euthyroidism.

The thyrotoxic phase is due to thyroid follicular damage and release of preformed hormone and is characterised by low thyroid uptake on nuclear scan and elevated ESR or CRP.

Thyroid pain and tenderness, which may be migratory and affect different areas of the gland at different times, is typical of the thyrotoxic phase. Thyroid is often enlarged, firm, and tender to palpation.

Ultrasound of the thyroid shows areas of hypoechoic echotexture with decreased or normal vascular flow by Doppler.

The condition is self-limited, and no specific therapy is generally necessary. Non-steroidal anti-inflammatory drugs and beta-blockers may be used for symptoms. Some patients with severe symptoms may also require corticosteroids, opioid analgesics, or potassium iodide or iopanoic acid to reduce the conversion of T4 to the more biologically active form of thyroid hormone, T3.

Definition

Subacute granulomatous thyroiditis is a self-limited inflammation of the thyroid gland. It is associated with a triphasic clinical course that lasts for a few weeks to many months, characterised by transient thyrotoxicosis, hypothyroidism, and then a return to normal thyroid function in >90% of patients. [1] [2] The initial thyrotoxic phase is associated with thyroid pain, high serum thyroid hormone levels with a low radioiodine uptake, elevated ESR, elevated CRP, and a systemic illness similar to influenza, with fever, myalgia, and malaise. [3] [4] [5]