Myxedema Coma or Crisis Treatment & Management

Myxedema crisis/coma is a life-threatening condition; therefore, patients with this disorder must be stabilized in an intensive care unit. The first 24-48 hours are critical. If the diagnosis is considered likely, immediate and aggressive administration of multiple interventions is necessary to lower an otherwise high rate of mortality. Initial priorities include the following:

• Mechanical ventilation if respiratory acidosis/hypercapnia/hypoxia is significant
• Immediate intravenous thyroid hormone replacement while awaiting confirmatory test results (T4 and TSH), even if the diagnosis of myxedema coma is only probable.

  • Because GI absorption is compromised, intravenous therapy is mandatory. Whether to use T4 alone, combined T4 and T3, or T3 alone remains a subject of controversy. Deiodinase conversion of T4 to the active hormone T3 is reduced in these patients, and T3 administration may be advisable. However, T3, because of its more immediate action and short half-life, may be more likely to cause arrhythmias, particularly if myocardial function is compromised. The usual conversion to an intravenous dose of T4 is approximately one half to two thirds of the oral dose.
  • An intravenous loading dose of 500-800 mcg of levothyroxine is followed by a daily intravenous dose of 50-100 mcg; the daily dose is administered until the patient is able to take medication by mouth. Use caution in elderly persons and in patients with coronary artery disease or myocardial infarction, because full-dose T4 therapy may worsen myocardial ischemia by increasing myocardial oxygen consumption.{Ref9}. Some authorities advocate the use of additional intravenous T3, at 10-20 mcg every 8-12 hours, especially in young patients with low cardiovascular risk.
  • Because of the rarity of the condition, randomized trials comparing different treatment modalities are not available. Observational studies are not in agreement regarding whether low^{[10, 11]} or high dose T4 or T3 replacement reduces mortality.^[7]
• In light of the possibility of adrenal insufficiency, stress steroid replacement after a cortisol level is obtained.^[12]
• After a baseline cortisol level is ascertained, initiate hydrocortisone at 5-10 mg/hr. Continue therapy unless the random cortisol level on admission indicates adrenal function without abnormalities, in which case, hydrocortisone may be stopped without tapering.
• Passive rewarming using ordinary blankets and a warm room (rapid and external rewarming are contraindicated)
• Treatment of associated infection
• Correction of severe hyponatremia (sodium level < 120 mEq/L) with saline, free water restriction
• Broad-spectrum antibiotics with modification of the antibiotic regimen based on culture results
• Correction of hypoglycemia with intravenous dextrose
• Treatment of severe hypotension with cautious administration of 5-10% glucose in half-normal or normal saline (or hypertonic saline if severely hyponatremic, ie, < 120 mEq/L)
• Dose adjustment of any medication to compensate for decreased renal perfusion, drug metabolism, etc
• Infection

  • The precipitating event in myxedema coma/crisis is often overt or occult bacterial infection.
  • Fever and elevated white blood cell (WBC) count are usually absent, although a left shift and/or bands may be observed.
  • Pan-culture and initiate empiric broad-spectrum antibiotic treatment, which can be narrowed if the source of infection is identified.
  • If culture results remain negative, antibiotics may be discontinued.
• Myocardial ischemia^[13]

  • Myocardial infarction may be the precipitating event in older patients, or it may subsequently occur.
  • Serial CK determinations with fractionation assist in the diagnosis and treatment of an acute coronary event. CK levels are often elevated in myxedema coma/crisis but are usually of muscle origin.
  • If ischemia or infarction is diagnosed, or if the patient has significant risk factors for coronary artery disease, institute thyroid replacement at low doses.
• Volume status

  • Intravenous glucose and normal saline should be carefully administered, because patients are usually volume overloaded and prone to congestive heart failure from the reduced cardiac function of hypothyroidism. If severely hyponatremic (sodium level < 120 mEq/L), consider administration of small amounts of hypertonic saline followed by intravenous furosemide to improve volume status.
  • Generally, hypotension is resistant to the usual drugs until thyroid hormone and glucocorticoids (if insufficient) are administered. If hypotension does not improve with prudent fluid replacement, whole blood can be transfused. Finally, cautious administration of dopamine can be used.

Stabilize patients in myxedema coma on T4 and glucocorticoids prior to surgical procedures. In life-threatening situations, administer a loading dose of T4 and glucocorticoids before induction of anesthesia. Careful cardiovascular monitoring with a Swan-Ganz catheter is required.

• Endotracheal intubation - Decreased ventilatory drive, CO ₂ retention, and hypoxemia all necessitate mechanical respiratory assistance to prevent cardiovascular collapse and worsening of hypoxia and hypercapnia.
• Cardiac monitoring in an intensive care unit

  • Myxedema coma/crisis is a medical emergency and requires close monitoring and stabilization.
  • Patients are at risk of myocardial ischemia.
• Central venous pressure or Swan-Ganz catheter monitoring - Hypotension signifies loss of blood volume from bleeding or vascular redistribution and must immediately be corrected.
• Temperature monitoring - This requires the use of a rectal probe to determine true core temperature and to monitor rewarming.

• Endocrinologist
• Critical care
• Consultations with the following practitioners may be necessary, depending on complications:

  • Infectious disease specialists
  • Pulmonologists
  • Cardiologists

Motility of the GI tract is usually decreased; therefore, withhold food until the patient is alert and extubated and normal bowel sounds are present; at that time, gradually introduce soft foods.

Once stable, patients may progress to usual activity as their strength allows. Physical therapy may be useful for patients who are debilitated.