Thyroid Storm vs Myxedema Coma on the NCLEX
The two thyroid emergencies: triggers, findings, and priority order for each.
Both are the extreme ends of thyroid disease, and both kill. Everything about them is opposite except the urgency.
Thyroid storm: everything too fast and too hot
Severe hyperthyroidism pushed over the edge by a trigger: infection, surgery, trauma, DKA, or abruptly stopping antithyroid drugs. Findings: very high fever, severe tachycardia and dysrhythmias (atrial fibrillation), hypertension progressing to heart failure and shock, agitation, tremor, delirium, nausea, vomiting, diarrhea. Untreated mortality is high.
Thyroid storm priorities
Airway, O2, continuous cardiac monitoring, IV fluids. Cool the patient, but no aspirin: salicylates free more thyroid hormone from its binding proteins. Use acetaminophen and cooling measures. Med order matters: beta-blocker (propranolol) for the cardiac symptoms; antithyroid drug (PTU or methimazole) to stop hormone production; THEN iodine, at least an hour after the antithyroid drug, to block hormone release. Corticosteroids reduce T4-to-T3 conversion. Treat the trigger.
Myxedema coma: everything too slow and too cold
Severe hypothyroidism collapsed by a trigger: infection, cold exposure, sedatives or opioids, or stopping levothyroxine. Classic patient: an older woman in winter. Findings: hypothermia, bradycardia, hypotension, hypoventilation with CO2 retention, hyponatremia, hypoglycemia, and declining consciousness to coma. Everything is low.
Myxedema coma priorities
Airway and ventilation first: hypoventilation is the immediate threat, and intubation is often needed. IV levothyroxine replaces the missing hormone. IV hydrocortisone is given as well until coexisting adrenal insufficiency is ruled out. Warm passively with blankets. Avoid active external rewarming: it vasodilates a patient with no cardiac reserve and drops the pressure. Correct glucose and sodium, treat the trigger, and avoid sedatives and opioids, which suppress the drive to breathe further.
Frequently asked
Why no aspirin for the thyroid storm fever?
Aspirin displaces thyroid hormone from binding proteins, raising free hormone and feeding the storm. Use acetaminophen and cooling blankets.
Why does myxedema coma get hydrocortisone?
Adrenal insufficiency can coexist, and thyroid replacement without steroid cover can precipitate adrenal crisis. Steroids run until it is excluded.
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