Subtypes Causes Hashimoto's thyroiditis, Chronic lymphocytic thyroiditis,[1] Chronic autoimmune thyroiditis, Lymphadenoid goiter[5] Autoimmune[3] Subacute lymphocytic thyroiditis, Postpartum thyroiditis, Sporadic painless thyroiditis,[3] Silent sporadic thyroiditis[5] Autoimmune[3] Acute infectious thyroiditis, Microbial inflammatory thyroiditis, Suppurative thyroiditis,[3] Pyrogenic thyroiditis, Bacterial thyroiditis[5] Cause: Bacterial, Parasitic, Fungal[3] de Quervain's thyroiditis, Subacute granulomatous thyroiditis,[3] Giant-cell thyroiditis, Pseudogranulomatous thyroiditis, Painful subacute thyroiditis,[5] Viral[3] Riedel's thyroiditis, Riedel's struma, Invasive fibrous thyroiditis Unknown[3]