Myxedema refers to a severe form of hypothyroidism than can occur when the condition is left untreated or is not treated sufficiently. The term also applies to the effects that hypothyroidism can have on the skin, making it appear swollen and puffy.

When thyroid hormone levels become extremely low, a person may experience symptoms such as drowsiness, confusion, and hypothermia, as well as changes to the skin.

One life-threatening complication of hypothyroidism is myxedema coma. This complication is also known as myxedema crisis, which is a more accurate term, as a person experiencing myxedema coma may not fall into a comatose state.

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Goiter is a symptom of severe hypothyroidism.
Image credit: Drahreg01, 2007

Myxedema occurs because of severe hypothyroidism that is not diagnosed or is not treated successfully. A person ceasing to take their medication can cause this complication.

Hypothyroidism develops because the thyroid stops working as it should. Causes of hypothyroidism include:

  • surgical removal of the thyroid
  • medications that affect the hormone system, such as some for cancer treatment
  • radiation therapy to treat cancer
  • other medications, including lithium, beta-blockers, and anesthesia
  • autoimmune conditions, such as Hashimoto’s thyroiditis
  • iodine deficiency or an excess of iodine
  • pregnancy
  • sudden illness or infection

Myxedema is a serious condition. Any person displaying symptoms of myxedema or severe hypothyroidism must receive medical attention urgently.

A person with myxedema may notice swelling in their face, legs, or tongue. Their skin may also become dry and pale.

Other symptoms of severe hypothyroidism can include:

Myxedema can also lead to low oxygen and high carbon dioxide levels in the blood.

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A person with myxedema may have swollen feet.

Hypothyroidism is treated with a synthetic version of the T4 thyroxine hormone called levothyroxine. This restores T4 hormone levels and can help relieve associated symptoms.

A person with myxedema is likely to stay in an intensive care unit with continual monitoring and treatment, and recovery may take several weeks.

A myxedema coma requires immediate admission to a hospital. Treatment involves administering thyroid hormone replacement medication into a vein. Antibiotics, steroid treatment, and breathing support may be necessary also.

A person may need breathing assistance, such as continuous positive airway pressure (CPAP) if carbon dioxide levels in the blood are very high. Doctors will also monitor heart rhythms and blood pressure carefully.

A person who recovers from myxedema will need to continue to take medication, probably for the rest of their life.

A doctor will make a diagnosis after seeing if a person’s symptoms are consistent with severe hypothyroidism. They may also perform a blood test to be sure.

A person with a high level of thyroid-stimulating hormone (TSH) may have hypothyroidism, as the body may produce extra TSH to make up for the underactive thyroid. As a result, a doctor may measure how much TSH a person’s pituitary gland produces.

A thyroxine or T4 test can also be taken to measure a person’s T4 level. Low levels of T4 are a good indicator of hypothyroidism, especially if combined with high levels of TSH.

If a doctor believes that a person has hypothyroidism, they will perform more tests to measure thyroid function and to find an underlying cause.

If a doctor suspects myxedema coma, they will recommend that treatment begins immediately. The sooner a person is treated, the more likely they are to recover.

Complications of myxedema include:

Myxedema coma is a rare but severe complication of myxedema. It is a life-threatening complication with a mortality rate of 25–60 percent and tends to affect older adults.

Symptoms of myxedema coma include a severe drop in body temperature, reduced breathing, and central nervous system failure, alongside other symptoms of hypothyroidism.

The sooner a person with advanced hypothyroidism receives treatment, the less likely they are to develop dangerous complications. Even with treatment, the mortality rate for a person with myxedema coma is relatively high.

A person has a much higher chance of recovery if myxedema is recognized and treated early with thyroid replacement therapy and supportive care.

Lifelong treatment to manage hypothyroidism is necessary, but if the condition is well-controlled, it will not affect the person’s life expectancy.