The etiology of subacute granulomatous thyroiditis (SAT) is obscure, although it 
is postulated to be associated with viral infections and genetic factors. In the 
present study, the possibility of an infectious etiology was prospectively 
studied in 27 consecutive patients with SAT. Special emphasis was put on the 
role of enteroviruses. Coupled sera (interval one month) were taken from all 
patients and single sera from 29 control subjects for virus antibody 
determinations. Stool samples were collected for virus isolation and fine-needle 
aspiration samples from thyroid gland for the detection of enterovirus RNA using 
RT-PCR were taken from SAT patients. Enteroviral antibodies were tested using 
three different methods: indirect EIA, heavy chain capture RIA, and standard 
complement fixation (CF) test. Antibodies against other common viral pathogens, 
including enteroviruses, were screened using the CF test and those against 
Mycoplasma pneumoniae and Chlamydia pneumoniae using EIA and 
microimmunofluorescence techniques, respectively. Common respiratory viruses 
were also screened from nasopharyngeal suction samples by antigen detection EIA. 
Based on serological findings, one patient had acute Cytomegalovirus infection. 
All other patients were negative in antibody tests, virus isolation, RT-PCR, and 
antigen detection. Enterovirus RNA was not detected by PCR in the thyroid tissue 
in any of the fine-needle aspiration samples. There was no evidence of recent 
enteroviral infections in SAT patients. The results suggest that SAT is not 
usually associated with acute infections. No evidence was obtained to support 
the proposed role of enteroviruses as an important etiologic agent of SAT.