• Myxedema coma is a critical, life-threatening decompensation of hypothyroidism requiring rapid recognition and treatment.
• These patients should be placed in a resuscitation bay on a monitor with advanced airway equipment at the bedside.
• Treatment must often be started empirically with potentially toxic doses of thyroid hormone that may precipitate thyroid storm.

• Myxedema coma or decompensated hypothyroidism is characterized by the triad of altered mental status, hypothermia and a precipitating event. The triggers of myxedema coma can be remembered with the DIMES mnemonic (see Table 1).

• The typical patient profile is an older female with signs of severe chronic hypothyroidism presenting in the winter. The clinical features of myxedema coma are listed in Table 2.

• The differential diagnosis of myxedema coma is broad and can be approached with the DIMES or AEIOU TIPS mnemonics for altered mental status.

• Myxedema coma is often a clinical diagnosis with support by a severely elevated TSH.
• Two clinical decision tools have been developed. Rosen’s recommends the Myxedema Coma Screening Tool to aid in diagnosis and treatment decisions (specificity and sensitivity of ~80%). However, this tool requires further validation and should be used with caution. Early consultation with internal medicine, endocrinology, and/or critical care is indicated to assist in diagnosis and management.

Criteria:

• GCS
  • 0-10: 4 points
  • 11-13: 3 points
  • 14: 2 points
  • 15: 0 points
• TSH
  • >30 mU/L: 2 points
  • 15-30 mU/L: 1 point
• Free T4
  • <7.72 pmol/L: 1 point
• Hypothermia
  • <35°C: 1 point
• Bradycardia
  • <60 bpm: 1 point
• Precipitating event
  • See Table 1: 1 point

Total Score and recommendations:

• 8-10: diagnosis is most likely; treat
• 5-7: likely; treat if no alternative diagnosis
• <5: unlikely; consider alternative diagnosis

• Supportive care and stabilization
  • Large bore IV access.
  • Monitors.
  • Intubation and ventilation, if indicated.
  • Hypotension
    • Gentle fluid resuscitation with NS +/- dextrose to treat any concomitant hyponatremia and hypoglycemia (use fluids with caution as aggressive volume resuscitation can unmask CHF).
    • Early IV thyroid hormone (see below).
    • Some patients may require vasopressor support (e.g., norepinephrine) until thyroid hormone replacement takes effect.
  • Hypothermia
    • Passive rewarming with blankets to prevent further heat loss.
    • If active rewarming, pre-treat and monitor for hypotension.
  • Hyponatremia and/or hypoglycemia
    • Treat as above and per standard protocol.
• IV thyroid hormone replacement
  • Levothyroxine (T4)
    • Loading dose
      • 4 mcg/kg IV (~200-400 mcg).
      • 100 mcg if elderly, small or history of coronary artery disease or arrhythmia.
    • Maintenance
      • 100 mcg IV 24 hours later, then 50 mcg IV q daily until tolerating PO (1.6 mcg/kg PO daily).
  • Add triiodothyronine if persistent hemodynamic instability or poor respiratory effort. However, use with caution in cardiac patients due to risk of arrhythmias or infarction.
    • Loading dose
      • 5-20 mcg IV
      • 5-10 mcg if elderly, small or history of coronary artery disease or arrhythmia
    • Maintenance
      • 2.5-10 mcg IV q8H until patient is conscious and tolerating PO
• Stress dose steroids for possible adrenal insufficiency.
• Hydrocortisone 100-200 mg IV q8H.
• Identify and treat precipitating factors (see Table 1).

Patients with myxedema coma require admission, endocrinology evaluation, and, depending on severity, ICU consultation.

• Depends on local guidelines.

1. https://www.bcemergencynetwork.ca/clinical_resource/hypothyroidism-diagnosis-treatment/

   
   

1. Thiessen MEW. Thyroid and Adrenal Disorders. In: Walls RM, Hockberger RS, Gausche-Hill M, Erickson TB, Wilcox SR, editors. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia (US): Elsevier; 2023. p. 1566-1585.

   
   

2. Cimino-Fiallos N. Decompensated Hypothyroidism. In: Mattu A, Swadron S, editors. CorePendium [Internet]. Burbank, CA: CorePendium, LLC; 2021 Jan 07 [cited 2023 May 24]. Available from: https://www.emrap.org/corependium/chapter/recq2Rb31DrFS9QWD/Decompensated-Hypothyroidism#h.qgt33a39yakc

   
   

3. Chiong YV, Bammerlin E, Mariash CN. Development of an objective tool for the diagnosis of myxedema coma. Transl Res [Internet]. 2015 Jan [cited 2023 May 24];166(3):233-43. Available from: http://dx.doi.org/10.1016/j.trsl.2015.01.003

   
   

4. Idrose A. Hypothyroidism and Myxedema Crisis. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH, editors. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide [Internet]. 9th ed. United States: McGraw Hill Medical; 2020 [cited 2023 June 7]. Chapter 228. Available from: https://accessmedicine.mhmedical.com/content.aspx?sectionid=190237546&bookid=2353&Resultclick=2