Subacute thyroiditis

Last reviewed: 22 Aug 2023
Last updated: 24 Jan 2023



History and exam

Key diagnostic factors

  • neck pain
  • tender, firm, enlarged thyroid
  • fever
  • palpitations
More key diagnostic factors

Other diagnostic factors

  • recent viral infection
  • myalgia
  • malaise
  • tremor
  • heat intolerance
Other diagnostic factors

Risk factors

  • viral infection
  • Certain HLA and B35 alleles
More risk factors

Diagnostic investigations

1st investigations to order

  • serum thyroid-stimulating hormone (TSH)
  • serum total T4, total T3, free T3, free T4 index, and free T4
  • T3:T4 ratio
  • radioactive iodine uptake
  • Serum ESR
  • Serum CRP
  • Serum thyroid antibodies (thyroid peroxidase antibodies [TPO Ab])
More 1st investigations to order

Investigations to consider

  • fine needle aspiration biopsy
  • complete blood count
More investigations to consider

Emerging tests

  • ultrasonography of thyroid

Treatment algorithm


hyperthyroid (thyrotoxic) phase

hypothyroid phase



Angela M. Leung, MD, MSc

Associate Professor of Medicine

UCLA David Geffen School of Medicine

VA Greater Los Angeles Healthcare System

Los Angeles



AL has served on the board of directors of the American Thyroid Association. She is editor-in-chief of Clinical Thyroidology, a journal of the American Thyroid Association. AL is a speaker for Medical Education Resources and MCE Conferences. She has consulted for Vertice Pharma and received article process charges paid by IBSA Institut Biochimique for an invited review article. AL has lectured at a conference sponsored by Merck and presented educational content for the Endocrine Society and the American Association of Clinical Endocrinology. AL is an advisor to Medscape and has received research funding from the U.S. Dept of Veterans Affairs.


Dr Angela M. Leung would like to gratefully acknowledge Dr Stephanie L. Lee, the previous contributor to this topic.


SLL declares that she has no competing interests.

Peer reviewers

Georg Hennemann, MD

Professor of Medicine and Endocrinology

Medical Center Spijkenisse

The Hague

The Netherlands


Not disclosed.

Ronald Merrell, MD

Professor of Surgery

Virginia Commonwealth University




RM declares that he has no competing interests.

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