History and exam

Key diagnostic factors

common

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

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

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

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

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

Myalgia may resemble that of a systemic viral illness.

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

Tremors may be caused by high circulating thyroid hormone levels.

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

Risk factors

strong

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

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][12]​​​​​​​​

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