<prompt> Hypothyroidism is caused by?LithiumHemochromatosisSclerodermaAll of the above  <response>: ANSWER: D All of the aboveREF: Harrisons Principles of Internal Medicine 17th ed-chapter 335Causes of HypothyroidismPRIMARYAutoimmune hypothyroidism: Hashimotos thyroiditis, atrophic thyroiditisIatrogenic: Iodine-131 treatment, subtotal or total thyroidectomy, external irradiation of neck for lymphoma or cancerDrugs: iodine excess including iodine-containing contrast media and amiodarone, lithium, antithyroid drugs, p-aminosalicyclic acid, interferon- and other cytokines, aminoglutethimide Congenital hypothyroidism: absent or ectopic thyroid gland, dyshormonogenesis, TSH-R mutation Iodine deficiencyInfiltrative disorders: Amyloidosis, Sarcoidosis, hemochromatosis, scleroderma, cystinosis, Riedels thyroiditis, Overexpression of type 3 deoiodinase in infantile hemangioma TRANSIENTSilent thyroiditis, including postpartum thyroiditisSubacute thyroiditisWithdrawal of thyroxine treatment in individuals with an intact thyroidAfter 1311 treatment or subtotal thyroidectomy for Graves diseaseSECONDARYHypopituitarism: tumors, pituitary surgery or irradiation, infiltrative disorders, Sheehans syndrome, trauma, genetic forms of combined pituitary hormone deficiencies Isolated TSH deficiency or inactivity Bexarotene treatmentHypothalamic disease: tumors, trauma, infiltrative disorders, idiopathic 