What is Myxedema?

Myxedema coma is a rare and severe result of hypothyroidism, a condition where the thyroid doesn’t produce enough hormones. This complication can cause abnormal function in many organs and confusion in the person it affects, potentially resulting in death if not treated promptly. When someone is hypothyroid, their body adapts in different ways to cope with the lack of thyroid hormone. If an additional factor like an infection occurs, it can overburden these coping mechanisms, leading to myxedema coma. Anyone with hypothyroidism, regardless of what caused it, can develop myxedema coma. But even with early discovery and treatment, the survival rate can vary. Some studies show it as high as 60%, while others report it between 20% to 25%, even with intensive care in the hospital.

People often use the term ‘myxedema’ when they’re talking about hypothyroidism and myxedema coma, but it actually refers to swelling of the skin and soft tissue that can occur in hypothyroidism. However, the name ‘myxedema coma’ is a little misleading. Patients don’t usually have non-pitting edema, which is swelling that doesn’t indent when you press on it. Also, they’re not usually in a coma. The most noticeable feature of myxedema coma is a progressive decline in mental function.

The best approach to managing myxedema coma involves suspecting the condition early, admitting the patient to an intensive care unit, and treating the patient with intravenous levothyroxine and hydrocortisone (medications to replace the hormones that the thyroid isn’t making). The medical team should assess the patient for any history of thyroid dysfunction, use of thyroid medication, adherence with thyroid medication, thyroid surgery, or use of any drugs that could affect thyroid function.

What Causes Myxedema?

Patients with hypothyroidism can sometimes go into a condition known as myxedema coma when their body’s normal balance is upset. This can be triggered by several factors including:

Infections – like urinary tract infections, pneumonia, viral infections and influenza
Physical harm – such as burns, carbon dioxide build-up in the body, injuries or trauma
Conditions – such as extremely low body temperature (hypothermia) or low blood sugar (hypoglycemia)
Lack of oxygen (hypoxemia) and stroke
Certain drugs – including amiodarone, lithium, sedatives, tranquilizers, anesthetics, opioids, phenytoin, rifampin, and water pills (diuretics), as well as beta-blockers (given that people with hypothyroidism break down drugs more slowly, they can accidentally overdose on anesthetics and tranquilizers)

There have also been documented cases of people developing myxedema coma after being treated with anti-TNF therapy, often used for autoimmune diseases.

Other triggers can include heart failure, bleeding in your digestive tract, and surgery (because it can affect the relationship between your pituitary gland and thyroid and lower your thyroid hormone levels). There have been cases where a condition called diabetic ketoacidosis, which happens when your blood sugar is very high, caused myxedema coma in a patient after having their thyroid removed.

Risk Factors and Frequency for Myxedema

The true number of myxedema coma cases is uncertain, though it’s estimated at around 0.22 per 1 million people each year in the western world. Data from other countries is not adequate to get a precise understanding. Myxedema coma tends to affect females more, accounting for 80% of cases, which is consistent with the fact that hypothyroidism is more common in women, being four times more likely than in men. It’s more likely to happen to people over 60 years old. In addition, due to lower heat production with age and in those with hypothyroidism, and decreased ability to regulate body temperature with age, myxedema coma is more common during winter, making up 90% of cases.

Signs and Symptoms of Myxedema

When people are severely hypothyroid (their thyroid isn’t working properly), they might need emergency medical assistance. Usually, these patients have mental confusion and a lower body temperature, below 35.5°C (95.9° F). The colder they are, the more critical their situation might be. If a person with severe hypothyroidism doesn’t have slightly high blood pressure, it could be a sign they’re at risk of entering a state of myxedema coma – an extremely dangerous condition that needs immediate medical attention.

Getting a full medical history can be tricky, especially if the patient’s mental state is disturbed. However, it’s crucial to know about their past thyroid problems, how obedient they are in taking their thyroid medication, whether they’ve had thyroid surgery, and if they are taking any drugs that can affect the thyroid. A thorough physical examination is critical too, as it could reveal signs of past thyroid problems like having no palpable thyroid tissue, sparse hair, swelling that doesn’t pit with pressure, a surgical scar on the neck, dry skin, or slow movements. However, elderly patients might not show these typical signs and instead, present with reduced mobility.

Mental changes can range from subtle such as moodiness, disinterest, poor mental performance, confusion, a short attention span, and disorientation, to severe such as psychosis and coma. Patients with decreased alertness should be checked for depression.
Breathing problems and sleep apnea
Lower body temperature. However, note that not all patients are cold, some may have a normal body temperature.
Skin that’s dry, cool, and feels doughy (swelling that doesn’t indent with pressure)
Hair loss
Slowness and decreased movement
Delayed reflexes
Change in blood pressure from high to low
Slow heart rate
Problems with the bladder, leading to its distention
Bloated abdomen and possibly paralytic ileus which can lead to mega colon (enlarged colon)
Fecal impaction (constipation that’s so severe, it can’t be relieved without medical help. A rectal examination is always a must in these patients)

Testing for Myxedema

If you are a woman with a history of thyroid disorders, especially during the cold winter months, your doctor might suspect you have myxedema coma if you come in with altered consciousness and a lower than normal body temperature. These are the most common symptoms. You might also have sodium levels that are too low (hyponatremia), low blood pressure (hypotension), slow heart rate (bradycardia), and shallow or slow breathing (hypoventilation).

Your doctor will also note other common signs of the condition, including low levels of certain thyroid hormones (serum total T4, free T4, free T3) and an elevated thyroid-stimulating hormone (TSH). If your TSH isn’t as high as expected, it could mean you have what’s called a euthyroid sick syndrome. In rare cases, if your TSH is inappropriately low, it might mean you have central hypothyroidism. This is usually confirmed when other hormones produced by the pituitary gland are also low.

Other lab tests might reveal you have normocytic or macrocytic anemia or a low white blood cell count (leukopenia). You might have high levels of creatine phosphokinase, which could lead to a misdiagnosis of heart attack. You could also have high levels of liver enzymes (transaminases), unusually high cholesterol due to reduced activity of an enzyme that breaks down fats in your blood (lipoprotein lipase), low blood sugar (hypoglycemia), and an elevated creatinine level along with low sodium levels due to reduced ability of your kidneys to excrete water.

Your doctor may also need to rule out infection. To do this, they may need to run a septic workup which might include taking cultures and conducting a chest X-ray. An electrocardiogram (EKG) might reveal a slow heart rate and other non-specific changes. Arterial blood tests might show low oxygen levels, high carbon dioxide levels, and respiratory acidosis – an excess of carbon dioxide in your blood. Further tests might be needed if your heart looks enlarged on an image. Tests such as an echocardiogram can help determine if there is fluid around your heart, a condition known as pericardial effusion. If your doctor suspects a neurological issue, they may recommend a lumbar puncture which can sometimes reveal high protein levels and non-specific changes in brain activity based on an EEG test.

A study done in 2014 proposed a way to score a person’s likelihood of having myxedema coma. The system examines the functioning of different body systems and whether someone has experienced a previous significant medical event. The score can help determine the risk of developing myxedema coma. A score of 60 or above is potentially diagnostic, while scores between 45 and 59 indicate an elevated risk.

Treatment Options for Myxedema

Having myxedema coma can be serious and has a high mortality rate, especially in elderly women and those who have heart rhythm problems, continued low body temperature, lowered consciousness, and infections. Therefore, it’s crucial that patients are cared for in an intensive care unit. Treatment involves dealing with multiple organ systems and identifying the trigger for the condition.

One of the key aspects of treating a patient with myxedema coma involves managing their breathing and keeping their airways open. Regular monitoring of the patient’s blood gas levels is essential to keep track of the high levels of carbon dioxide (hypercapnia) and low levels of oxygen (hypoxemia) in their blood. Since the patient’s awareness can be affected by myxedema coma, they’re more prone to choking or obstructing their airway. This means that they might need mechanical ventilation and should continue to receive ventilator support until their hypercapnia and hypoxemia levels are normal and they regain consciousness.

In such patients, body warming measures (against hypothermia) need to be done slowly, else it could lead to a fall in blood pressure (hypotension) and shock. Similarly, the administration of fluids should be monitored carefully to avoid any further fall in blood pressure.

Patients with myxedema coma ought to be checked for potential infections, such as monitoring their urine and blood for harmful microorganisms. In case severe blood sodium deficiency (hyponatremia) is detected, which can affect mental functioning, a cautious balance should be maintained between restricting and providing fluids. Caution should be exercised in correcting the sodium levels as too rapid an increase might cause nerve damage.

Initiating thyroid hormone treatment as quickly as possible is crucial in managing myxedema coma. The treatment should include hydrocortisone, especially in patients with low blood pressure, to avoid a sudden drop in adrenal hormone levels (adrenal crisis) that might occur when thyroid hormone treatment is started. The dose of thyroid hormone medication should be adjusted based on continuous monitoring of thyroid levels.

Although treatment with a combination of thyroid hormones can lead to a significant improvement in the patient’s condition within two days of starting treatment, the optimal treatment approach is still debatable, particularly for older patients and those with heart diseases. Similarly, although it’s well-known that severe illness can decrease metabolism to protect organ function, whether this process can be applied to patients with myxedema coma remains unclear.

One key point to remember is that the seriousness of myxedema coma shouldn’t solely depend on high levels of the thyroid-stimulating hormone (TSH), since it might not always reduce in response to treatment. It’s better to expect serum free thyroxine (FT4)—a thyroid hormone—to normalize within four days of starting treatment.

If someone is experiencing an altered mental state or is in a coma, the doctor may consider several different potential causes for these symptoms. These could include:

Sepsis, a severe infection that can spread throughout the body,
Shock, a life-threatening condition that requires immediate medical attention,
Stroke, a condition where blood flow to the brain is blocked,
Drug overdose, which can lead to unconsciousness or even death,
Diabetic ketoacidosis, a serious complication that can occur in people with diabetes,
Seizure, a sudden, uncontrolled electrical disturbance in the brain,
Hypothermia, a medical emergency that occurs when your body loses heat faster than it can produce heat.

These are just possible causes, and the doctor would need to perform more tests to confirm the actual cause.

What to expect with Myxedema

It’s hard to determine the outlook for people with myxedema coma because there aren’t many reported cases. The death rate varies a lot – in some cases as much as 60%, but in other cases it’s as low as 20 to 25% if the patient receives advanced intensive care. The chances of recovery can be lower in older people, and those who continue to have a slow heart rate (bradycardia) and persistently low body temperature (hypothermia).

Possible Complications When Diagnosed with Myxedema

Myxedema coma can be deadly if it is not treated. Complications from myxedema can lead to very serious health problems. The major issues include falling into a coma, problems with breathing, heart issues, infections that can spread in the body, and severe bleeding in the gut.

Myxedema coma that can be fatal when untreated
Breathing problems
Heart conditions
Widespread infections in the body
Severe internal bleeding in the digestive system

Preventing Myxedema

It’s essential for patients to understand how vital it is to consistently take their medications and monitor their thyroid function, especially after starting certain medications like amiodarone, lithium, and anti-TNF. Consistent compliance ensures the medicine works properly, while regular thyroid monitoring can identify any potential health concerns early.