Causes of Hypothyroidism
| Primary |
| Autoimmune hypothyroidism: Hashimoto's thyroiditis, atrophic thyroiditis |
| Iatrogenic: 131I treatment, subtotal or total thyroidectomy, external irradiation of neck for lymphoma or cancer |
| Drugs: iodine excess (including iodine-containing contrast media and amiodarone), lithium, antithyroid drugs, p-aminosalicylic acid, interferon α and other cytokines, aminoglutethimide, sunitinib |
| Congenital hypothyroidism: absent or ectopic thyroid gland, dyshormonogenesis, TSH-R mutation |
| Iodine deficiency |
| Infiltrative disorders: amyloidosis, sarcoidosis, hemochromatosis, scleroderma, cystinosis, Riedel's thyroiditis |
| Overexpression of type 3 deiodinase in infantile hemangioma |
| Transient |
| Silent thyroiditis, including postpartum thyroiditis |
| Subacute thyroiditis |
| Withdrawal of thyroxine treatment in individuals with an intact thyroid |
| After 131I treatment or subtotal thyroidectomy for Graves' disease |
| Secondary |
| Hypopituitarism: tumors, pituitary surgery or irradiation, infiltrative disorders, Sheehan's syndrome, trauma, genetic forms of combined pituitary hormone deficiencies |
| Isolated TSH deficiency or inactivity |
| Bexarotene treatment |
| Hypothalamic disease: tumors, trauma, infiltrative disorders, idiopathic |
Abbreviations: TSH, thyroid-stimulating hormone; TSH-R, TSH receptor.