History and exam
Key diagnostic factors
common
neck pain
tender, firm, enlarged thyroid
The thyroid is often enlarged, firm, and tender to palpation.[4]
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
In one retrospective cohort study of 852 patients, 23% reported symptoms of an upper respiratory tract infection within 1 month of the onset of subacute thyroiditis.[1]
Seasonal variation has been reported in several studies, whereby increased subacute thyroiditis incidence coincides with peak enterovirus incidence.[1][7][8]
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
In one retrospective cohort study of 852 patients, 23% reported symptoms of an upper respiratory tract infection within 1 month of the onset of subacute thyroiditis.[1]
Seasonal variation has been reported in several studies, whereby increased subacute thyroiditis incidence coincides with peak enterovirus incidence.[1][7][8]
Viral antibody titres tend to be high at the onset of the illness and fall with time.[7][11]
specific human leukocyte antigen (HLA) allele
Histocompatibility studies show a predominance of certain HLA alleles in patients with subacute thyroiditis.[6][18][19][20]
The HLA-B*35 allele is present in approximately 81% of patients with subacute thyroiditis.[20] Familial cases of subacute thyroiditis associated with HLA-B*35 have been observed.[21]
Subacute thyroiditis has also been associated with HLA-B*18:01, -DRB1*01, and -C*04:01.[3][19][20]
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