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Myxedema Coma: Symptoms, Causes, & Emergency Treatment

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Written by Tim Becker, MD.
Resident Physician, The Mount Sinai Hospital
Last updated May 19, 2023

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This article will review the symptoms, causes, and management of myxedema coma. Myxedema coma is a rare complication of severe hypothyroidism and a life-threatening medical emergency.

What is myxedema coma?

Myxedema coma is a rare complication of severe hypothyroidism and a life-threatening medical emergency. Hypothyroidism is a relatively common condition involving the underproduction of hormones by the thyroid.

Symptoms of hypothyroidism can be vague but involve fatigue, weight gain, constipation, and cold intolerance, among others. Symptoms of myxedema coma include altered mental status (possibly to the point of being unarousable), swelling, very low body temperature, low heart rate, low blood pressure, abdominal pain, and lung dysfunction.

Treatment is needed immediately and will require medications to regulate thyroid levels and fluids and to address any underlying triggers, such as antibiotics for an infection.

You should go to the ER immediately, where doctors will evaluate your blood, and if the diagnosis is confirmed, start you on treatment.

Symptoms of myxedema coma

Symptoms of myxedema coma are severe and people typically require treatment in the intensive care units of hospitals for pulmonary and vascular support. People who are not treated quickly often do not survive.

Symptoms of hypothyroidism

Symptoms of hypothyroidism are detailed below. Some people with hypothyroidism, however, are completely asymptomatic because other body systems compensate for the thyroid’s deficiencies.

  • Fatigue: Feeling tired easily and generally lacking energy
  • Weight gain: Gaining weight despite no major changes in diet or activity levels
  • Constipation: Bowel movements occur with decreased frequency, often resulting in hard stool that may require straining and be painful to release.
  • Cold intolerance: People with hypothyroidism find they feel cold even when others find a room’s temperature comfortable.
  • Dry, pale, cool skin: Skin is often dry with sparse, coarse hair.
  • Hoarse voice: In moderate to severe hypothyroidism voice changes may occur.
  • Decreased mobility: Difficulty moving around has been noted as a symptom, particularly in older people with hypothyroidism.

Symptoms of myxedema coma

Symptoms specific to this condition are detailed below.

  • Altered mental status: People may become confused or unarousable. This may start as merely decreased motivation or slight cognitive impairment but can proceed to disorientation (such as being confused about the time and place), hallucinations, seizures, or being unresponsive to voice or touch.
  • Swelling of skin and soft tissues (edema): Skin can become puffy, with the tongue enlarging and the eyes appearing swollen. Shoes may not fit well due to enlargement of the feet.
  • Very low body temperature (hypothermia): Body temperature can fall below 95.9 degrees Fahrenheit.
  • Slow heart rate (bradycardia)
  • Arrhythmias: The heart can develop abnormal electrical activity.
  • Abdominal pain: Severe constipation can lead the gut to retain stool, leading to crampy pain and an enlarged abdomen.
  • Blood clots (coagulation disorder)
  • Lung dysfunction: The diaphragm becomes weak and the body doesn’t compensate adequately for low oxygen.
  • Low blood pressure: Various factors can contribute to this, including a low heart rate and low blood volume, resulting in lower blood pressure.

What causes a myxedema coma?

The thyroid is a hormone-producing (endocrine) organ in the neck that controls the body’s metabolism. Hypothyroidism, the underproduction of hormones by the thyroid, is a common condition that affects 5-10% of the population. Myxedema coma is a rare complication of the most severe hypothyroidism. It is somewhat of a misnomer, as people can be in myxedema coma without being truly comatose (deeply unconscious), although mental impairment is common.

Causes of hypothyroidism

Most people who develop myxedema coma have had hypothyroidism for a long time, although it might have never been detected or diagnosed. Hypothyroidism has several causes. These include:

  • Autoimmune: Attacks by the body’s immune cells on the thyroid cells, such as Hashimoto thyroiditis, can leave the remaining thyroid underproductive of hormones.
  • Surgery: The thyroid is sometimes intentionally removed or destroyed to treat cancer or other thyroid diseases, resulting in the need to take thyroid replacement hormones for the rest of life.
  • Iodine deficiency: Iodine is necessary early in development for the thyroid to grow properly. Children who are malnourished of iodine from birth can have hypothyroidism from birth.
  • Rare genetic diseases: This may lead to impairment in the production of hormones.
  • Medications: Such as lithium and amiodarone, can interfere with thyroid hormone release


The body typically makes adjustments to compensate for the lack of thyroid hormone. However, when the body is overwhelmed by other stressors, such as an infection, the body systems may lose their balance, leading to myxedema coma.

  • Influenza:
  • Pneumonia:
  • Urinary tract infections and urosepsis
  • Sepsis: A condition of inflammation throughout the body that can cause multiple organs to fail

Other stressors

In addition to infection, other various stressors that can also result in myxedema coma include:

  • Discontinuation of thyroid replacement medications
  • Heart attack (Myocardial infarction): This is when the heart muscle does not get enough oxygen.
  • Stroke: This is when the brain does not get enough oxygen.
  • Burns: Specifically moderate and severe burns
  • Trauma: Injuries and broken bones
  • Low blood sugar (hypoglycemia)
  • Consumption of raw bok choy
  • Surgery: Recovering from surgery places significant stress on multiple body systems. Also, exposure to anesthesia medications used during surgery may precipitate myxedema.
  • Certain medications: Amiodarone, barbiturates, beta blockers, diuretics, lithium, opioids, phenytoin, rifampin

Other risk factors for myxedema coma

Other various risk factors include the following.

  • Elderly: Most people are over 60 years old.
  • Winter: More than 90% of cases occur in the winter. This is possibly due to the difficulty of recognizing that one’s temperature is low during colder weather.
  • Female: Four out of five cases occur in women.

Treatment options and prevention for myxedema coma


Treatment often entails various medications to address both thyroid levels and other issues.

  • Replacement thyroid hormones: The major underlying problem in myxedema is a lack of thyroid hormones. This problem can directly be corrected by administering replacement hormones, such as levothyroxine (T4), intravenously.
  • Hydrocortisone: Since the thyroid and adrenal glands are both controlled by the pituitary, pituitary failure can result in simultaneous adrenal failure and myxedema. Therefore, steroid replacement (the treatment for adrenal failure) is often administered initially until adrenal failure is ruled out.
  • Antibiotics: Myxedema is commonly triggered by infections, so antibiotics are often an important part of treatment.

Correction of other abnormalities

Other specific abnormalities of the body may arise and will be addressed accordingly.

  • Fluid levels: People with myxedema often have fluid and electrolyte abnormalities, such as low sodium in the blood, which can be corrected with replacement fluids and careful monitoring of labs.
  • Warming: People with low body temperature can be warmed with blankets and heat.
  • Mechanical ventilation: Decreased lung function may require breathing support from a machine.

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When to seek further consultation for myxedema coma

If you have symptoms of hypothyroidism

Many of the symptoms of hypothyroidism are subtle and non-specific. However, if you experience symptoms such as unexplained weight gain, constipation, dry skin, and low energy, consider asking your doctor if screening for a thyroid disorder may be appropriate, particularly if you have a family history of thyroid or autoimmune diseases.

If you or someone you know has hypothyroidism and experiences declines in cognition

If you or a loved one, particularly if elderly and in the winter, has hypothyroidism and has a rapid decline in cognition and/or swelling of the face and limbs, contact your doctor so that worsening hypothyroidism can be detected early before severe illness develops.

If you or someone you know stops taking their thyroid medications

Thyroid replacement medications are typically needed for the rest of one’s life. If the medication is discontinued, although the body may compensate initially (resulting in little experience of symptoms) once the body is stressed, myxedema and its severe consequences can result. If you or someone close to you has not been taking thyroid medicine, contact your physician about restarting.

Questions your doctor may ask to determine myxedema coma

  • How long has this been going on?
  • How severe is your headache?
  • How long has your current headache been going on?
  • Have you lost your appetite recently?
  • Are you sick enough to consider going to the emergency room right now?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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