History and exam

Key diagnostic factors

common

neck pain

Pain of the anterior neck may range from moderate to severe, accompanied by an inability to swallow or tolerate a physical examination. The pain may sometimes radiate to the ears or jaw.

tender, firm, enlarged thyroid

The thyroid is often enlarged, firm, and tender to palpation.[15]

fever

Approximately 30% of patients have a temperature between 37°C (98.6°F) and 38°C (100.4°F). Another 30% of patients have fever >38°C (100.4°F).[1]

palpitations

Palpitations may occur in >70% of patients who have symptoms of thyrotoxicosis.[1]

This is caused by fever and high circulating thyroid hormone levels.

Other diagnostic factors

common

recent viral infection

Approximately 25% to 30% of patients report a viral infection within 1 month before the onset of subacute thyroiditis.[1]

myalgia

Myalgia may resemble that of a systemic viral illness.

malaise

Malaise may be caused by a viral infection, and can be seen in association with fever and high circulating thyroid hormone levels.

tremor

Tremors may be caused by high circulating thyroid hormone levels.

heat intolerance

Heat intolerance may be caused by fever and high circulating thyroid hormone levels.

Risk factors

strong

viral infection

Approximately 30% to 40% of patients with subacute thyroiditis describe a viral infection within 1 month of onset. The peak incidence coincides with the summer to autumn seasons, which is the peak incidence of many other viral infections. Viral antibody titres tend to be high at the onset of the illness and fall with time.[8][9]

Certain HLA and B35 alleles

The HLA-B*35 allele is present in about 70% of patients with subacute thyroiditis.[11] Familial occurrence of subacute thyroiditis has been seen with HLA-B35.[13]​ Subacute thyroiditis has also shown to be associated with HLA-B*18:01, -DRB1*01, and -C*04:01.[3][17]​​​​​​​

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