eMedicine Specialties > Endocrinology > Thyroid

Myxedema Coma or Crisis: Treatment & Medication

Author: Elena Citkowitz, MD, PhD, FACP, Clinical Professor of Medicine, Yale University School of Medicine; Director, Cholesterol Management Center, Director, Cardiac Rehabilitation, Department of Medicine, Hospital of St Raphael
Contributor Information and Disclosures

Updated: Aug 5, 2008

Treatment

Medical Care

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^9,10 or high dose T4 or T3 replacement reduces mortality.⁶
• In light of the possibility of adrenal insufficiency, stress steroid replacement after a cortisol level is obtained.¹¹
• 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 ischemia¹²
  • 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.

Surgical Care

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.

Consultations

• Endocrinologist
• Critical care
• Consultations with the following practitioners may be necessary, depending on complications:
  • Infectious disease specialists
  • Pulmonologists
  • Cardiologists

Diet

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.

Activity

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

Medication

The goals of pharmacotherapy are to increase thyroid hormone levels, reduce morbidity, and prevent complications.

Thyroid hormones

Immediate administration of intravenous levothyroxine is necessity if myxedema coma/crisis is considered likely. Controversy exists regarding whether additional treatment with T3 is necessary. When the patient is eating and ambulating, oral T4 may be substituted.

Levothyroxine (Synthroid, Levoxyl)

In active form, influences growth and maturation of tissues. Involved in normal growth, metabolism, and development. IV dosage form has a long half-life (may be administered qd and is the preferred route of administration in patients with myxedema coma/crisis because GI tract absorption may be compromised). Preferred by many authorities, because the onset of action is slow and sustained, making adverse effects less likely to occur and serum levels easier to monitor. Administering only T4 assumes normal conversion to T3 by deiodinase activity, which is usually compromised in severe illness. IV dose of T4 is approximately one half to two thirds of the PO dose. Lower doses recommended if patient has uncontrolled atrial arrhythmia or recent MI.

Liothyronine (Cytomel, Triostat)

Synthetic form of the natural thyroid hormone, T3, converted from T4. T3 is the active form, but because peripheral conversion of T4 to T3 is compromised in patients who are hypothyroid, some authorities suggest combined IV T4 and T3 in these patients. However, patients with cardiovascular disease are at greater risk of arrhythmia and infarction.

T3 has a short half-life and must be administered q8h. Because of concerns about abrupt onset and fluctuating concentrations in tissues, experts advise coadministration of T3 with T4.

Corticosteroids

Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. They modify the body's immune response to diverse stimuli.

Hydrocortisone (Solu-Cortef, Hydrocortone)

DOC because of mineralocorticoid activity and glucocorticoid effects. Patients presenting with myxedema coma/crisis may have adrenal insufficiency, and stress doses of IV steroids must be administered along with initial thyroid replacement until adrenal function has been determined to be normal.

• Search for CME/CE on This Topic »

• Thyroid Problems Overview
• Thyroid Problems Treatment
• Thyroid Problems Causes
• Thyroid Problems Symptoms
• Endocrine System Center
• Myxedema Coma Overview