Thyroid Emergencies (Storm and Myxedema Coma)
2
Emergencies
Thyroid storm (hyper) and myxedema coma (hypo)
1
Storm Treatment Order
PTU or methimazole FIRST, iodine 1 hour later
1
Coma Treatment
IV levothyroxine plus stress-dose steroids
Thyroid Storm
everything is running too fast and too hotSevere tachycardia, often with atrial fibrillation
Hyperthermia above 104°F (40°C)
Altered mental status ranging from agitation to delirium
PTU or methimazole FIRST to block hormone synthesis
Iodine (SSKI or Lugol) ONE HOUR after antithyroid drug
Beta-blockers (propranolol) to control heart rate
Hydrocortisone for adrenal support and conversion blockade
Active cooling with cooling blankets and acetaminophen
PTU or methimazole FIRST. Iodine 1 HOUR LATER. Giving iodine first worsens the storm.
Myxedema Coma
Hypothermia (may be severely low)
Bradycardia and hypotension
Altered mental status progressing to coma
IV levothyroxine (oral absorption unreliable in this state)
Stress-dose hydrocortisone before or with levothyroxine
Passive rewarming only (active rewarming causes vasodilation and cardiovascular collapse)
Key Values to Memorize
PTU before iodine (1 hr gap)
Propranolol for rate control
Hydrocortisone for both
IV levothyroxine for coma
Passive rewarming only
Acetaminophen NOT aspirin
thyroid emergencies are high-yield CCRN questions
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Practice CCRN QuestionsExam Traps
PTU before iodine always
Giving iodine before PTU or methimazole provides substrate for the thyroid to make even more hormone, worsening the storm. Block synthesis first, then block new iodine uptake one hour later. The exam loves to test this sequence.
Storm and coma are OPPOSITES
Thyroid storm presents with tachycardia, hyperthermia, and agitation. Myxedema coma presents with bradycardia, hypothermia, and obtundation. If you confuse the two, every treatment decision will be wrong.
Stress-dose steroids for both
Both thyroid storm and myxedema coma require stress-dose hydrocortisone. In storm, steroids block T4 to T3 peripheral conversion. In coma, steroids cover potential concurrent adrenal insufficiency. The exam tests whether you know steroids apply to both.
Iodine Timing
NEVER give iodine before PTU or methimazole. Wait one full hour. Giving iodine first feeds the storm.
Opposite Presentations
Storm = hot, fast, confused. Coma = cold, slow, confused. Both need steroids. Both are emergencies.
The thermostat is stuck on maximum. The furnace is blasting nonstop. The house is overheating, the fan is spinning out of control, and everything is running too fast. You have to shut off the gas (PTU) before you cap the gas line (iodine).
The thermostat is stuck on off. No heat at all. The house is freezing, everything slows to a crawl, pipes are about to burst. You have to carefully turn the heat back on (IV levothyroxine) without shocking the system.
In both emergencies, the backup generator (adrenals) may be failing too. Steroids keep that backup generator running while you fix the main thermostat.
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