Decompensated hypothyroidism (myxedema coma)

A 62 year old woman is brought into the emergency department by EMS after being found lethargic and confused. On arrival, she has a temperature of 34 degrees Celsius, a heart rate of 62, a blood pressure of 88/52, and an oxygen saturation of 92% on room air. The patient does not respond to voice, but withdraws and moans when touched, and doesn’t seem to have any focal neurologic deficits. About 20 minutes into the resuscitation, apparently knowing how hard the diagnosis of decompensated hypothyroidism (or myxedema coma) is to make, the family politely asks, “could this be related to her thyroid?”. Only then do you notice the scar on her neck and her thick waxy skin, and sheepishly ask the nurse to call the lab to add thyroid studies to the bloodwork you already sent.

My approach

Follow your approach to altered mental status (check a glucose)

In the first 10 minutes, you are unlikely to be managing “hypothyroidism”, because you won’t have made the diagnosis yet. Start with your general approach to altered mental status, which will include checking the glucose.

For more information about making the diagnosis of severe hypothyroidism, see the rapid review of the topic. The quick summary is that I am considering the diagnosis in anyone with altered mental status and either hypothermia or (relative) bradycardia.

Manage the airway

Start with basic airway maneuvers, but intubation will frequently be necessary, as a result of altered mental status, hypercapnia, and hypoxia. These patients often start hypoxic and hypercapnic, with a decreased functional capacity, and hemodynamic instability, so should be considered physiologically difficult airways. Additionally, hypothyroidism can cause edema of the tongue and larynx, resulting in anatomical difficulties with intubation that will not always be clinically apparent. (Bridwell 2021)

Manage the hemodynamics

Hypotension and hypoperfusion are common. Fluid boluses are used as the first line, but caution is required due to the possibility of low output heart failure. Hypotension is often refractory to vasopressors. The key to hemodynamic management is diagnosing hypothyroidism and treating it with thyroid hormone and steroids. (Bridwell 2021)

Give Steroids

Give hydrocortisone 100 mg IV.

The hydrocortisone should be given before administration of levothyroxine, as levothyroxine can precipitate an adrenal crisis. Steroids are also a key component of hemodynamic management, as adrenal insufficiency will frequently be a contributor to the patient’s hypotension. (Bridwell 2021; Jonklaas 2014)

Give levothyroxine (+/- T3)

Levothyroxine (T4) 200-400 mcg IV. (Consider a lower dose in elderly patients and those with significant cardiac disease). (Bridwell 2021; Farkas 2016; Jonklaas 2014) Because T4 is the inactive form of the hormone, it is safe to give this dose empirically if there will be a delay in obtaining lab results.

The use of T3 is more controversial, and the risk of adverse events is higher than with T4. Personally, I will do my best to talk with an endocrinologist before giving T3, but if I have a critically ill patient who hasn’t responded to T4 and I am pretty convinced of the diagnosis, I will give the loading dose of 5-10 mcg IV, with smaller doses for older patients or those with known cardiac disease. (Jonklaas 2014, Farkas 2016)

Identify the underlying cause

Severe hypothyroidism is usually triggered by an underlying cause which needs to be rapidly identified and managed. (Bridwell 2021) My memory gets worse and worse each year, so I will just come back to this checklist:

• Infection
• MI
• CVA
• GI bleed
• Surgery
• Trauma
• Intoxication
• Medications
  • Amiodarone
  • Lithium
  • Iodinated contrast
  • Opioids,
  • Sedatives
  • SSRIs
  • Beta-blockers
  • Antipsychotics

Sepsis is the most common cause, and has many overlapping features. Empiric antibiotics in the emergency department will almost always be warranted.

Supportive care is very important

High quality supportive care – including diligent management of temperature, electrolytes, fluids, respiration, and hemodynamics – is essential.

There is some concern that active rewarming could result in peripheral vasodilation and hemodynamic collapse, although the evidence for that is questionable. Start with passive rewarming with blankets and ensure the room is warm. (Bridwell 2021) 

Hypoglycemia and hyponatremia are very common. An ICU level of attention is essential (and therefore the best step in management might simply be to transfer the patient from the emergency department to the ICU). 

If seizures occur, use your standard (aggressive) status epilepticus algorithm, but keep in mind that secondary causes, such as hypoglycemia, hypoxia, and hyponatremia, are more common and need to be urgently diagnosed and managed. (Bridwell 2021)

In severe cases, ECMO has been used to provide hemodynamic support and active rewarming. (Bridwell 2021)

Other FOAMed Resources

Severe Hypothyroidism Rapid Review (more info on diagnosis)

EMCrit offers us some excellent opposing opinions on the role of T3 in the management of severe hypothyroidism: EMCrit 292 – IV T3 for Myxedema Coma, A Different Take with Eve Bloomgarden and EMCrit 290 – Decompensated Hypothyroidism and Myxedema with Dr. Arti Bhan

IBCC: Decompensated Hypothyroidism (“Myxedema Coma”)

REBEL Core Cast 16.0 – Decompensated Hypothyroidism

References

Bridwell RE, Willis GC, Gottlieb M, Koyfman A, Long B. Decompensated hypothyroidism: A review for the emergency clinician. Am J Emerg Med. 2021 Jan;39:207-212. doi: 10.1016/j.ajem.2020.09.062 PMID: 33039222

Farkas, J. Decompensated Hypothyroidism (“Myxedema Coma”). In: Internet Book of Critical Care (IBCC). 2016. Available: https://emcrit.org/ibcc/myxedema/

Jonklaas J, Bianco AC, Bauer AJ, Burman KD, Cappola AR, Celi FS, Cooper DS, Kim BW, Peeters RP, Rosenthal MS, Sawka AM; American Thyroid Association Task Force on Thyroid Hormone Replacement. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014 Dec;24(12):1670-751. doi: 10.1089/thy.2014.0028. PMID: 25266247

Kwaku MP, Burman KD. Myxedema coma. J Intensive Care Med. 2007 Jul-Aug;22(4):224-31. doi: 10.1177/0885066607301361. PMID: 17712058