Viral infections: are they real players in thyroiditis?
Résumé
Different viruses have been found in various thyroid biopsies. Different viruses are then possibly involved in the onset of thyroiditis; however onset of thyroiditis is certainly depending on the patient's genetic background. Patients infected by the HIV have subclinical hypothyroidism or low fT4, especially when they are treated with some old antiviral treatments. There's no autoimmunity leading to the hypothesis on a iatrogenic effect. Graves' disease is observed in patients with severe lymphopenia before treatment and is part of the immune reconstitution syndrome. VHC can infect thyrocytes and thyroid could constitute an extrahepatic reservoir for HCV viral replication. Subacute thyroiditis is due to IFN treatment but HCV infection of thyrocytes might play a role in thyroid autoimmunity. Part of its genetic background has been identified. Enteroviruses, especially the diabetogenic C8V4, can replicate in thyroid cells and can persist, with predominance of viral negative RNA strands. Enterovirus-RNA can be detected in thyroid biopsies from patients with various thyroid diseases, but it's not more frequent in thyroiditis. The presence of erythrovirus B19 is observed in biopsies of different thyroid disease including Graves' disease. There is, however, no proof of a relationship between its presence and thyroiditis.