Thyroid Storm

Thyroid storm, or thyrotoxic crisis, is acute decompensation caused by thyrotoxicosis. It is not defined by a particular free T4 or free T3 concentration. Patients with uncomplicated thyrotoxicosis and patients in storm may have similarly elevated hormone levels; the distinction is the development of organ dysfunction. Thyroid hormone increases oxygen consumption, heat production, myocardial contractility, and gastrointestinal activity. It also increases beta-adrenergic receptor sensitivity, so ordinary circulating catecholamines produce an exaggerated response. The result can be severe tachycardia, atrial fibrillation, widened pulse pressure, high-output heart failure, hyperthermia, agitation, delirium, vomiting, diarrhea, jaundice, and eventually shock. A precipitant such as infection, surgery, trauma, an iodine load, or abrupt discontinuation of antithyroid medication can push a previously compensated patient into multisystem failure. An experienced clinician notices the combination rather than any isolated finding: a very fast heart rate that seems disproportionate to the fever, new mental-status change, and evidence of cardiac, gastrointestinal, or hepatic injury. Fever alone is not storm. A suppressed TSH alone is not storm. Consider a patient with Graves disease who stopped methimazole two weeks ago and now has...