Autoimmune-mediated inflammation of the thyroid gland with release of thyroid hormone resulting in transient hyperthyroidism, frequently followed by a hypothyroid phase before recovery of normal thyroid function.
Occurs sporadically, postnatally, or during immuno-modulatory or lithium therapy.
Some patients progress to permanent hypothyroidism early, others years or decades later.
The diagnosis can be confirmed by a 4-, 6-, or 24-hour radioiodine uptake of <1% during the hyperthyroid phase of the illness.
Treatment, if needed, includes beta-blockers for the hyperthyroid phase and levothyroxine for the hypothyroid phase of the illness.
The condition is characterised by an autoimmune-mediated lymphocytic inflammation of the thyroid gland resulting in a destructive thyroiditis with release of thyroid hormone and transient thyrotoxicosis (hyperthyroidism).[1]Pearce EN, Farwell AP, Braverman LE. Thyroiditis. N Engl J Med. 2003 Jun 26;348(26):2646-55.
https://www.doi.org/10.1056/NEJMra021194
http://www.ncbi.nlm.nih.gov/pubmed/12826640?tool=bestpractice.com
[2]Woolf PD. Transient painless thyroiditis with hyperthyroidism: a variant of lymphocytic thyroiditis? Endocr Rev. 1980 Fall;1(4):411-20.
http://www.ncbi.nlm.nih.gov/pubmed/7018893?tool=bestpractice.com
[3]Samuels MH. Subacute, silent and postpartum thyroiditis. Med Clin North Am. 2012 Mar;96(2):223-33.
http://www.ncbi.nlm.nih.gov/pubmed/22443972?tool=bestpractice.com
This is frequently followed by a hypothyroid phase and full recovery.
The accepted nomenclature is controversial as many view painless thyroiditis as a variant presentation of chronic lymphocytic (Hashimoto's) thyroiditis, because Hashimoto's thyroiditis results in permanent hypothyroidism and permanent hypothyroidism may occur shortly after the hypothyroid phase of painless thyroiditis or during prolonged follow-up.[2]Woolf PD. Transient painless thyroiditis with hyperthyroidism: a variant of lymphocytic thyroiditis? Endocr Rev. 1980 Fall;1(4):411-20.
http://www.ncbi.nlm.nih.gov/pubmed/7018893?tool=bestpractice.com
[3]Samuels MH. Subacute, silent and postpartum thyroiditis. Med Clin North Am. 2012 Mar;96(2):223-33.
http://www.ncbi.nlm.nih.gov/pubmed/22443972?tool=bestpractice.com
[4]Nikolai TF, Brousseau J, Kettrick MA, et al. Lymphocytic thyroiditis with spontaneously resolving hyperthyroidism (silent thyroiditis). Arch Intern Med. 1980 Apr;140(4):478-82.
http://www.ncbi.nlm.nih.gov/pubmed/6892676?tool=bestpractice.com
The condition is particularly common in the postnatal period. However, the term postnatal thyroiditis also includes patients who experience only transient hypothyroidism due to an exacerbation of Hashimoto's thyroiditis.[5]Stagnaro-Green A. Clinical review 152: postpartum thyroiditis. J Clin Endocrinol Metab. 2002 Sep;87(9):4042-7.
http://press.endocrine.org/doi/full/10.1210/jc.2002-020524
http://www.ncbi.nlm.nih.gov/pubmed/12213841?tool=bestpractice.com
Autoimmune thyroid disease, which includes painless and Hashimoto's thyroiditis and Graves' disease, may arise during immuno-modulatory or lithium therapy.[6]Muller I, Moran C, Lecumberri B, et al. 2019 European Thyroid Association guidelines on the management of thyroid dysfunction following immune reconstitution therapy. Eur Thyroid J. 2019 Jul;8(4):173-185.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6738237
http://www.ncbi.nlm.nih.gov/pubmed/31602359?tool=bestpractice.com
[7]Carella C, Mazziotti G, Amato G, et al. Clinical review 169: interferon-a-related thyroid disease: pathophysiological, epidemiological, and clinical aspects. J Clin Endocrinol Metab. 2004 Aug;89(8):3656-61.
http://www.ncbi.nlm.nih.gov/pubmed/15292282?tool=bestpractice.com
[8]Miller KK, Daniels GH. Association between lithium use and thyrotoxicosis caused by silent thyroiditis. Clin Endocrinol (Oxf). 2001 Oct;55(4):501-8.
http://www.ncbi.nlm.nih.gov/pubmed/11678833?tool=bestpractice.com
[9]Ahmadieh H, Salti I. Tyrosine kinase inhibitors induced thyroid dysfunction: a review of its incidence, pathophysiology, clinical relevance, and treatment. Biomed Res Int. 2013;2013:725410.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824811
http://www.ncbi.nlm.nih.gov/pubmed/24282820?tool=bestpractice.com
[10]Torino F, Barnabei A, Paragliola R, et al. Thyroid dysfunction as an unintended side effect of anticancer drugs. Thyroid. 2013 Nov;23(11):1345-66.
http://www.ncbi.nlm.nih.gov/pubmed/23750887?tool=bestpractice.com
Finally, a destructive thyroiditis may occur in other settings where pathophysiology, evaluation, and treatment differ from painless thyroiditis. These include acute (suppurative),[11]Paes JE, Burman KD, Cohen J, et al. Acute bacterial suppurative thyroiditis: a clinical review and expert opinion. Thyroid. 2010 Mar;20(3):247-55.
http://www.ncbi.nlm.nih.gov/pubmed/20144025?tool=bestpractice.com
subacute (granulomatous, de Quervain),[12]Fatourechi V, Aniszewski JP, Fatourechi GZ, et al. Clinical features and outcome of subacute thyroiditis in an incident cohort: Olmstead County, Minnesota, study. J Clin Endocrinol Metab. 2003 May;88(5):2100-5.
http://press.endocrine.org/doi/full/10.1210/jc.2002-021799
http://www.ncbi.nlm.nih.gov/pubmed/12727961?tool=bestpractice.com
palpation,[13]Stang MT, Yim JH, Challinor SM, et al. Hyperthyroidism after parathyroid exploration. Surgery. 2005 Dec;138(6):1058-64.
http://www.ncbi.nlm.nih.gov/pubmed/16360391?tool=bestpractice.com
radiation-induced,[14]Aizawa T, Watanabe T, Suzuki N, et al. Radiation-induced painless thyrotoxic thyroiditis followed by hypothyroidism: a case report and literature review. Thyroid. 1998 Mar;8(3):273-5.
http://www.ncbi.nlm.nih.gov/pubmed/9545116?tool=bestpractice.com
and amiodarone-induced thyroiditis.[15]Basaria S, Cooper DS. Amiodarone and the thyroid. Am J Med. 2005 Jul;118(7):706-14.
http://www.ncbi.nlm.nih.gov/pubmed/15989900?tool=bestpractice.com