Table 1.

Risk factors associated with autoimmune thyroid disease

Risk factor		Mechanism
Genetic background/ family history of thyroid
	Major histocompatibility genes	↑Genetic susceptibility to environmental triggers
	Immunoregulatory genes
	Thyroid-specific genes
Environmental factors
	Dietary iodine	↑Immunogenicity of thyroglobulin, thyroid cell destruction
	Smoking	↑Cytokines in thyroid, complex interactions with the immune system
	Selenium	Interact with immune response
	Environmental toxicants / chemicals	Promote autoimmune thyroiditis in susceptible models
	Stress	Provocative factor in the pathogenesis of Graves' disease
	Drugs	Exogenous estrogens may protect against the development of antithyroid antibodies