Myxedema Coma in the ED: Frozen in Time

-Case-
A 68-year-old woman with a history of hypothyroidism is brought in by EMS for altered mental status. Family says she’s been increasingly tired, confused, and cold to the touch over the last few days. On exam, she’s hypothermic (34°C), bradycardic, and barely arousable. You get labs and note a severely elevated TSH and undetectable free T4. You’re staring down a rare but life-threatening endocrine emergency…

-Evaluation-
Despite the name, patients are often not in true coma; but they are sick. Myxedema coma lies at the severe end of the spectrum of hypothyroidism – untreated or undertreated, and often triggered by infection, cold exposure, medications (like sedatives), or MI.

  • Common symptoms: lethargy, altered mental status, hypothermia, dry skin, facial puffiness, macroglossia, bradycardia, hypotension, and (sometimes) seizures
  • Labs:
    • Elevated TSH, low free T4
    • Hypoglycemia
    • Hyponatremia
    • Hypoventilation and hypercapnia (from hypoventilation)
    • Possible elevated CK, liver enzymes, or hypoxia

Diagnosis:
This is a clinical diagnosis supported by labs. There is no specific scoring system used in the ED, but please suspect it in anyone with altered mental status, hypothermia, and known (or suspected) hypothyroidism.

-Management-

  • Supportive care first!
    • Warming blankets (no rapid rewarming)
    • Passive warming to prevent shock
    • Airway management for hypoventilation
    • IV fluids and vasopressors if hypotensive
  • Thyroid hormone replacement:
    • IV levothyroxine (T4) and consider IV liothyronine (T3) in severe cases or with poor/refractory response
  • Stress-dose steroids:
    • Hydrocortisone 100 mg IV q8h, started empirically until adrenal insufficiency is ruled out
  • Treat underlying triggers: infection, MI, medications, etc.

-Fast Facts-

  • Mortality can exceed 50% if not recognized and treated promptly
  • Often triggered by a secondary stressor (infection, MI, cold exposure)
  • T4 is preferred initially due to wider safety margin, but T3 may be added in severe cases
  • Always give steroids first in case of concurrent adrenal insufficiency!

In the ED, you don’t need a full endocrine workup to act. If you see an altered, bradycardic, hypothermic patient with known hypothyroidism, don’t wait. Start supportive care, call your endocrinologist, and initiate thyroid hormone replacement. Myxedema coma might be rare, but missing it could be fatal.

Want to learn more? Read our in-depth study guide and listen to our podcast episode on this topic!

Cheers,

Tamir Zitelny, MD

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-References-

  1. Wartofsky L. Myxedema coma. Endocrinol Metab Clin North Am. 2006;35(4):687-698. doi:10.1016/j.ecl.2006.09.010
  2. Klubo-Gwiezdzinska J, Wartofsky L. Thyroid emergencies. Med Clin North Am. 2012;96(2):385-403. doi:10.1016/j.mcna.2012.01.011
  3. Yamamoto T, Fukuyama J, Fujiyoshi A. Factors associated with mortality of myxedema coma: report of eight cases and literature survey. Thyroid. 1999;9(11):1167-1174. doi:10.1089/thy.1999.9.1167
  4. Law G, Kaur A, Anastasopoulou C. Myxedema Coma. StatPearls. Treasure Island (FL): StatPearls Publishing; 2024.
  5. Burch HB, Wartofsky L. Life-threatening thyrotoxicosis: thyroid storm. Endocrinol Metab Clin North Am. 1993;22(2):263-277.
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