3-10x more common in females
Peak incidence age >60
Emergent manifestation of severe hypothyroid = myxedema coma
Primary
Autoimmune (Hashimoto)
Thyroiditis (subacute, silent, postpartum)
Often preceded by hyperthyroid phase
Iodine deficiency
After ablation (surgical, radioiodine)
After external radiation
Infiltrative disease (lymphoma, sarcoid, amyloid, TB)
Congenital
Meds
Amiodarone, lithium, iodine, Interferon-α, interleukin
Idiopathic
Secondary
Panhypopituitarism
Pituitary adenoma
Infiltrative causes (e.g., hemochromatosis, sarcoidosis)
Tumors impinging on the hypothalamus
History of brain irradiation
Infection (e.g., tuberculosis)
Autoimmune (Hashimoto)
Thyroiditis (subacute, silent, postpartum)
Often preceded by hyperthyroid phase
Iodine deficiency
After ablation (surgical, radioiodine)
After external radiation
Infiltrative disease (lymphoma, sarcoid, amyloid, TB)
Congenital
Meds
Amiodarone, lithium, iodine, Interferon-α, interleukin
Idiopathic
Often preceded by hyperthyroid phase
Amiodarone, lithium, iodine, Interferon-α, interleukin
Panhypopituitarism
Pituitary adenoma
Infiltrative causes (e.g., hemochromatosis, sarcoidosis)
Tumors impinging on the hypothalamus
History of brain irradiation
Infection (e.g., tuberculosis)
Myxedema coma <<<unk>  < euthyroid > hyperthyroidism >> thyroid storm
Hypothyroidism
Addison's disease
Congenital adrenal hyperplasia
Chronic fatigue syndrome
Levothyroxine toxicity
Constipation
Hyperthyroidism
Depression