Myxedema Coma Symptoms, Causes, and Treatment

Coma is a state of decreased consciousness whereby a patient cannot react with the surrounding environment.

Myxedema (crisis) coma is a loss of brain function as a result of the severe, longstanding low level of thyroid hormone in the blood (hypothyroidism). Myxedema coma is considered a rare life-threatening complication of hypothyroidism and represents one of the more serious sides of thyroid disease.

Before a person develops myxedema coma, signs and symptoms of hypothyroidism usually are present and may have gone undiagnosed for a long time.

Symptoms of hypothyroidism include

• fatigue,
• lethargy,
• mental impairment,
• depression,
• cold intolerance,
• hoarseness,
• dry skin,
• weight gain,
• change in menstrual cycles,
• constipation, and
• headaches.

People with myxedema coma may have symptoms and signs, for example:

• The body temperature is usually abnormally low (hypothermia), the core temperature may be as low as 80 F (26.6 C);
• Severe mental changes including hallucinations, disorientation, seizures, and ultimately, deep coma;
• Significant swelling (edema) all over the body with swollen eyes and thickening of the tongue,
• Sparse, dry hair, and loss of the outer thirds of the eyebrows;
• Difficulty breathing;
• Collections of fluid around the lungs and heart (pleural effusion and pericardial effusions);
• The heart may slow down and its ability to pump blood forward can be impaired;
• The gastrointestinal tract does not function well and sometimes it becomes paralyzed, thereby necessitating surgery; and
• Blood test abnormalities are a result of the increased fluid in the body. For example, sodium levels drop because of dilution, which is caused by the body retaining extra water.

Most patients with myxedema coma have a history of hypothyroidism.

Most patients with myxedema coma have a history of hypothyroidism, thyroid surgery, or radioactive iodine treatment for thyroid disease. Very rarely, the problem is not caused by the inability of the thyroid gland to make thyroid hormone; but rather is caused by the failure of the pituitary gland or the hypothalamus to correctly signal the thyroid gland to perform its normal functions. In this situation, the thyroid gland is normal, but it is not receiving the signals from the pituitary gland or hypothalamus to make the thyroid hormone it is capable of producing.

Certain factors may suddenly trigger myxedema coma in a person with poorly controlled hypothyroidism. These include drugs (particularly sedatives, narcotics, anesthesia, lithium (Eskalith, Lithobid), and amiodarone (Cordarone), infections, stroke, trauma, heart failure, digestive (gastrointestinal, GI) bleeding, hypothermia (abnormally low body temperature), and failing to take thyroid medications as prescribed by their doctor.

Initial laboratory evaluation usually includes a test for thyroid function (TSH, T3 and T4 levels). Other blood tests and heart and lung function tests may be needed.

Treatment may include assisting the patient to breathe and warming them to raise the body temperature to normal. Often, antibiotics are started until it is certain that an infection is not present.

The method of replacing the thyroid hormone in patients with myxedema coma is controversial. Many different approaches are used. In general, initial replacement is done by intravenous infusion, since the intestinal system may not be absorbing properly.

While common hypothyroidism without myxedema is usually treated with T4 replacement (the hormone produced in greatest quantity by the thyroid gland), in the case of myxedema coma, management is different. The thyroid gland also produces a small amount of another hormone, T3. This is the more metabolically active of the two hormones. In patients who are well, T4 is converted into T3 in the bloodstream. However, patients with myxedema coma are often so sick that this conversion is impaired. As a result, many doctors choose to treat these patients with T3 initially and start T4 therapy as well. Since T4 therapy can take a month or so to work, there is usually an overlap of these two hormones. Care is taken to avoid heart rhythm abnormalities (arrhythmias) and stress on the heart, which can be caused by replacing thyroid hormone too quickly, particularly in elderly patients.

Mild thyroid disorders can be managed by primary or internal medicine doctors, however; it usually is managed by a thyroid specialist (endocrinologist) because treatment can be complicated and critical.

The ideal way to manage this condition is to prevent it from occurring in the first place. An individual with hypothyroidism should visit their doctor regularly for follow-up and blood testing to be certain that their replacement dose is appropriate.

If an individual has symptoms that concerns them, but has not beendiagnosed with hypothyroidism, they should visit their health care practitioner to discuss their concerns and explore the option of testing for thyroid imbalance.