What is the treatment for a patient presenting with symptoms of myxedema coma, including altered mental status, hypothermia, bradycardia, and respiratory depression?

Treatment of Myxedema Coma

Myxedema coma is a life-threatening endocrine emergency requiring immediate hospital admission with high-level care, intravenous levothyroxine, stress-dose corticosteroids (hydrocortisone must be given BEFORE thyroid hormone if central hypothyroidism cannot be excluded), and aggressive supportive measures for hypothermia, bradycardia, hypotension, and respiratory failure. 1

Immediate Recognition and Admission

• Admit to ICU or high-dependency unit immediately upon suspicion of myxedema coma—do not wait for laboratory confirmation given the high mortality rate 1, 2, 3, 4, 5, 6
• Classic presentation includes: altered mental status (lethargy, confusion, coma), hypothermia, bradycardia, hypotension, respiratory depression, and generalized edema 2, 3, 4, 5, 6
• Precipitating factors to identify: sepsis/infection, surgery, trauma, cold exposure, cerebrovascular accident, gastrointestinal bleeding, sedatives/anesthetics, or medication non-compliance 7, 2, 4, 6

Critical First Step: Rule Out Adrenal Insufficiency

ALWAYS give hydrocortisone BEFORE initiating thyroid hormone replacement if there is any uncertainty about whether primary or central hypothyroidism is present—failure to do so can precipitate life-threatening adrenal crisis. 1, 8

• Administer hydrocortisone (stress-dose corticosteroids) immediately until coexisting adrenal insufficiency is excluded 1, 9, 6
• This is non-negotiable in patients with suspected central hypothyroidism or hypophysitis 1, 8

Thyroid Hormone Replacement Protocol

Intravenous Levothyroxine

• Initiate IV levothyroxine immediately with endocrinology consultation to assist with dosing 1
• IV dose is approximately 50-75% of oral dose due to higher bioavailability 8
• For elderly patients (>70 years) or those with known cardiovascular disease: start with lower dose of 25-37.5 mcg IV daily and titrate gradually to avoid precipitating atrial fibrillation, myocardial ischemia, or cardiac decompensation 8
• For younger patients without cardiac risk factors: higher initial dosing may be appropriate 8

Intravenous Liothyronine (T3)

• Consider adding IV liothyronine (Triostat®) for myxedema coma, as it has more rapid onset of action 9, 3
• Liothyronine showed marked improvement in hypothermia and bradycardia when levothyroxine response was slow 3
• Typical duration: 6 days, then continue levothyroxine alone 3

Aggressive Supportive Care

Hypothermia Management

• For moderate hypothermia (28-32°C): implement active external rewarming with heating pads or forced warm air blankets, administer warmed IV fluids, provide humidified warmed oxygen 10
• For severe hypothermia (<28°C): continue all moderate hypothermia measures, activate emergency response, consider active core rewarming, handle patient gently to avoid triggering arrhythmias 10
• Target core temperature minimum of 36°C, cease rewarming at 37°C 10
• Monitor core temperature every 5-15 minutes depending on severity 10

Cardiovascular Support

• Bradycardia and hypotension may require vasopressor support 5
• Monitor for cardiogenic shock—echocardiography may reveal severely reduced left ventricular ejection fraction that improves with treatment 5
• Watch for cardiac arrhythmias during rewarming 10

Respiratory Support

• Mechanical ventilation may be required for respiratory failure 5
• Provide humidified warmed oxygen 10

Metabolic Corrections

• Immediately identify and correct hypoglycemia 7, 3
• Correct hyponatremia cautiously 3, 5
• Monitor and manage acute kidney injury 3, 4

Monitoring and Laboratory Assessment

Initial Workup

• Establish good IV access with wide-bore cannulas 1
• Consider arterial and central venous lines, insert urinary catheter 1
• Obtain: TSH, free T4, electrolytes (especially sodium and potassium), arterial blood gases, glucose, renal and hepatic function, coagulation studies 1, 10
• Check for infection markers and obtain cultures if sepsis suspected 3, 4

Ongoing Monitoring

• Monitor TSH and free T4 every 6-8 weeks during dose titration once stabilized 1, 8
• For patients with cardiac disease or atrial fibrillation: consider more frequent monitoring within 2 weeks 8
• Free T4 levels help interpret ongoing abnormal TSH, as TSH may take longer to normalize 1, 8

Common Pitfalls to Avoid

• Never start thyroid hormone before corticosteroids in suspected central hypothyroidism—this is the most critical error 1, 8
• Do not delay treatment waiting for laboratory confirmation—initiate therapy based on clinical suspicion 2, 6
• Avoid excessive initial dosing in elderly or cardiac patients 8
• Do not overlook precipitating factors, especially sepsis requiring urgent antibiotics 3, 4
• Watch for rewarming shock as peripheral vasodilation can precipitate cardiovascular collapse 10

Expected Clinical Course

• Hypothermia and bradycardia may be slow to respond initially but should show marked improvement within days of appropriate treatment 3
• Neurological status and thyroid function typically normalize over several days with intensive care 5
• Continue levothyroxine at maintenance dose (typically 175 mcg or adjusted to patient needs) after acute phase 3
• Arrange outpatient endocrinology follow-up for long-term management and medication adherence 3, 5