Is Hashimoto's Disease an Autoimmune Disease?
Yes, Hashimoto's thyroiditis (also called chronic autoimmune thyroiditis) is definitively an autoimmune disease characterized by thyroid-specific autoantibodies and lymphocytic infiltration of the thyroid gland. 1, 2
Defining Characteristics of Hashimoto's as an Autoimmune Disease
Hashimoto's thyroiditis is the most common autoimmune thyroid disorder and represents the leading cause of hypothyroidism in iodine-sufficient regions worldwide. 2, 3
The autoimmune nature of Hashimoto's disease is established by several key features:
Autoantibody production: The disease is characterized by the presence of thyroid peroxidase (TPO) antibodies and/or thyroglobulin antibodies in the serum, which are the biochemical hallmarks of the condition 2, 4
Lymphocytic infiltration: Histopathologic examination reveals T and B cell inflammatory infiltration of the thyroid gland, with lymphoid follicle formation and germinal centers 2, 5
Loss of self-tolerance: The pathogenesis involves a breakdown of immunological tolerance mechanisms, leading to an autoimmune attack against thyroid tissue 3, 5
Cellular and humoral immunity: Both T-cell mediated cytotoxicity and antibody-mediated autoimmune responses drive the destruction of thyrocytes 2, 4
Clinical Recognition in Guidelines
Multiple international guidelines explicitly classify Hashimoto's thyroiditis as an autoimmune disease and the most common cause of hypothyroidism in pregnant and postpartum women in industrialized nations. 1
The American College of Obstetricians and Gynecologists (ACOG) identifies chronic autoimmune thyroiditis (Hashimoto's disease) as the most frequent cause of hypothyroidism in industrialized countries, distinguishing it from iodine deficiency which predominates worldwide 1
Association with Other Autoimmune Conditions
Hashimoto's thyroiditis frequently clusters with other autoimmune diseases, further confirming its autoimmune classification. 1
The Korean Association for the Study of the Liver reports that autoimmune thyroid disease is the most common concurrent autoimmune condition in patients with autoimmune hepatitis, with Hashimoto's thyroiditis accounting for approximately 10.2-14.1% of all concomitant autoimmune diseases 1
Type 1 autoimmune hepatitis is commonly associated with autoimmune thyroid disease, while type 2 autoimmune hepatitis is associated with type 1 diabetes and autoimmune thyroid disease 1
Approximately 20% of patients with autoimmune thyroid disorders have other organ-specific or systemic autoimmune conditions 3
Pathogenic Mechanisms
The autoimmune pathogenesis involves:
Genetic susceptibility: Strong hereditary predisposition confirmed by family and twin studies, with associations to HLA genes, CTLA-4, PTPN22, and other immune-related genes 5
Environmental triggers: Iodine intake, infections, drugs, and chemical exposures can precipitate disease in genetically susceptible individuals 1, 5
Immune dysregulation: Predominantly Th1 and Th17 immune responses lead to progressive thyroid destruction through apoptosis and cytotoxic mechanisms 5, 6