Lymphocytic thyroiditis is the most common autoimmune disease, usually affecting young women. Although the aetiology and pathogenesis remain obscure, the most widely accepted hypothesis is an interaction between a genetic predisposition and an environmental trigger factor such as viral infection. Parvovirus infections have been proposed as trigger factors for Hashimoto's thyroiditis and Graves' disease.

Inclusion Criteria:

• Graves' disease :patients treated for Graves' disease, the diagnosis date less than 4 months
• Control : patients cared for nodules or goiter

Exclusion Criteria:

• Patients undergoing immunosuppressive therapy including corticosteroids