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Myxedema and Hypothothyroidism

Learn about myxedema, a rare but life-threatening complication of untreated hypothyroidism.
Myxedema and Hypothothyroidism
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From regulating your body temperature to digestive functions, the thyroid gland -- and the hormones it produces -- play essential roles in your body. Every cell needs thyroid hormone to function. But, sometimes, things go awry, and you develop a thyroid disorder such as hypothyroidism or hyperthyroidism.

In this article, we focus on myxedema, a rare but severe complication of hypothyroidism.

Understanding hypothyroidism

Hypothyroidism, a common endocrine disorder, affects 5 to 10% of the American population. It occurs when the thyroid fails to make enough thyroid hormones, including thyroxine (T4) and triiodothyronine (T3).

HPT feedback loop

A feedback loop called the hypothalamus-pituitary-thyroid (HPT) axis regulates thyroid hormone production. Here’s how.

The hypothalamus, a region in the brain, detects low thyroid hormone levels. In response, the hypothalamus releases thyrotrophin-releasing hormone (TRH), which signals the pituitary gland to release thyroid-stimulating hormone (TSH). In turn, TSH acts on the thyroid to trigger the production and release of T4 and T3.

When thyroid hormones reach the appropriate level in the body, TRH and TSH secretion stop. But as your body uses up T4 and T3, and there’s a drop in the level of these hormones in your bloodstream, TRH and TSH secretion start again. And the cycle continues.

Your thyroid mainly produces T4, the inactive form of thyroid hormone. Cells in your body convert T4 to its active form, T3. For your cells to benefit from thyroid hormone, it must be in the T3 form.

Symptoms of hypothyroidism

A lack of thyroid hormone affects the function of nearly every cell in your body. Here are some of the more common symptoms of hypothyroidism to be aware of:

Treatment of hypothyroidism

The treatment of hypothyroidism focuses on increasing thyroid hormone levels in the body. Typically, this is done by taking a daily thyroid hormone replacement medication such as levothyroxine or natural desiccated thyroid (NDT). Other treatment options include supplements and lifestyle modifications such as adjustments to one’s diet or stress management.

Hypothyroidism is a chronic medical condition, meaning there is no cure. And you will likely need to take thyroid medication for the rest of your life. Untreated hypothyroidism can lead to heart issues, fertility troubles, and myxedema.

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Myxedema: a serious complication of hypothyroidism

Myxedema is a medical condition marked by profound swelling, altered mental status, and, in some cases, a comatose state. This condition manifests when hypothyroidism reaches an advanced stage. Myxedema occurs when T3 levels in your cells drop extremely low, preventing your cells from functioning.

Close to 95% of cases of myxedema stem from primary hypothyroidism, which occurs when there is damage to the thyroid gland, thus affecting thyroid production. The most common cause of primary hypothyroidism is Hashimoto’s thyroiditis, an autoimmune disorder.

Myxedema primarily affects older individuals, especially women. But, it can occur in anyone, as illustrated by a recent case report of myxedema in a 39-year-old male. There also appears to be a seasonal trend, with more hospital admissions for myxedema occurring during winter.

Clinical presentation of myxedema

The onset of myxedema is linked to a drastic drop in T3 within the cells. Since all cells need T3 to function, without it, signs and symptoms of myxedema become evident and include: 

  • Low body temperature (hypothermia)
  • Slow heart rate (bradycardia)
  • Low blood pressure (hypotension)
  • Low blood sugar (hypoglycemia)
  • Change in mental status
  • Delayed tendon reflexes
  • Puffiness in the face, hands, and feet (edema)
  • Enlarged tongue or thyroid gland
  • Electrolyte abnormalities

It is important to know that those who take a diuretic, a “water pill,” may not present with typical signs and symptoms of myxedema. Diuretics remove excess fluid, preventing fluid retention and edema, two usually prominent features of myxedema.

Over time, if left untreated, myxedema can lead to a loss of consciousness, known as myxedema coma. 

Causes and triggers

There are many potential causes for myxedema, with infections, including septicemia, being the most common culprit. Septicemia is a severe infection when bacteria enter your bloodstream and travel throughout your body. Often, septicemia arises from an infection such as a urinary tract infection, cellulitis (skin infection), or pneumonia.

Additionally, there are non-infection-related triggers of myxedema, such as:

  • Stroke
  • Congestive heart failure
  • Gastrointestinal bleeding
  • Trauma such as a car accident or surgery
  • Medications including sedatives, pain medications, amiodarone, and lithium

Furthermore, overdoing certain foods, like raw bok choy (Chinese white cabbage), may also trigger myxedema. When broken down by the body, bok choy produces byproducts that interfere with iodine uptake in the thyroid. Without enough iodine, your thyroid can’t make thyroid hormone.

Lastly, stopping and staying off prescribed thyroid hormone replacement medications can also trigger myxedema.

Diagnosis and testing

Despite the severity of myxedema, there are no clear diagnostic criteria. Generally, healthcare providers diagnose myxedema based on clinical presentation and lab values, especially those related to your thyroid.

When the underlying thyroid disorder is primary hypothyroidism, those with myxedema generally present with a significantly high TSH level and low T4 levels.

Treatment approaches for myxedema

Myxedema is a medical emergency that requires immediate medical attention. While rare, this condition does carry a high mortality rate (risk of death.) Those with myxedema may experience a change in body temperature ranging from a slight decrease to a drastic drop. Research links the severity of hypothermia at the time of medical care as one of the predictors of death.

Why is your body temperature linked so closely to survival? Your cells generate heat during a process called thermogenesis. Without T3, your cells can no longer perform thermogenesis, causing your body temperature to drop. When this happens, your breathing and heart rate slow down, and you begin to shiver and may slur your speech. In some cases, individuals may even lose consciousness and fall into myxedema coma. Maintaining a core body temperature between roughly 97 to 99 degrees for adults (the range varies based on age) is necessary for your body to function.

Most often, individuals presenting with symptoms of myxedema are admitted to the hospital for comprehensive management. The treatment approach is multifaceted and includes:

  • Supportive care such as mechanical ventilation support or heart monitoring
  • Fluid management and correction of low blood pressure and electrolyte levels
  • Aggressive management of precipitating factors, like starting antibiotics for an infection
  • Thyroid hormone supplementation with replacement medication


Thyroid hormone replacement therapy

Thyroid hormone replacement therapy is the mainstay of treatment for those with myxedema. Like natural thyroid hormone production, thyroid replacement is available as T4, T3, or a combination.

With the administration of T4, levels in the hypothyroid patient rise quickly, surpassing normal levels. T4 is then converted to T3 by the cells. As thyroid hormone levels rise, TSH levels will drop, helping to get the HPT feedback loop working again. But this all takes time.

In contrast, T3 therapy works quicker in the body because it is already in the active form. But how much T3 your body absorbs, especially if given in the tablet formulation, varies. And T3 may add extra stress to the heart in some sensitive people.

Some experts recommend giving both T4 and T3 during myxedema, while some still lean towards T4 monotherapy. In a 2022 case report, a patient received both T4 and T3 with good results. However, combination therapy for myxedema remains controversial.


Taking the following steps to manage hypothyroidism can help prevent myxedema.

  1. Regular thyroid function monitoring: Monitoring your thyroid function through blood tests or at-home testing kits helps identify abnormalities in thyroid hormone levels. The earlier these abnormalities are detected, the better. Schedule regular follow-up visits with your provider to discuss thyroid results and other concerns.
  2. Medication adherence: If your healthcare provider prescribes thyroid medication, take it as prescribed. Consistently taking your thyroid medication ensures your body receives the necessary hormones to maintain optimal function. Don’t stop taking your thyroid medication without talking to your provider first.
  3. Lifestyle choices: A healthy lifestyle can support well-being and promote thyroid health. This includes maintaining a balanced diet or following a thyroid-friendly one, regular physical activity, managing stress, and getting quality sleep.

While there are standard treatment algorithms for managing hypothyroidism, treatments may vary for each individual based on their needs. Here at Paloma Health, we take a personalized approach to managing hypothyroidism. We offer patients with hypothyroidism effective, evidence-based integrative treatment options. Get started with one of our thyroid experts today.


American Thyroid Association. Hypothyroidism: risk factors for death in patients with myxedema coma. Clinical Thyroidology for the Public. 2017;10(4):3-4.

Mathew V, Ahmad Misgar R, Ghosh S, Mukhopadhyay P, Roychowdhury P, Pandit K, et al. Myxedema Coma: A New Look into an Old Crisis. J Thyroid Res. 2011.

Santos Argueta A, Doukas SG, Roy R. New-Onset Hypothyroidism Manifesting As Myxedema Coma: Fighting an Old Enemy. Cureus. 2022;14(4): e23881. doi:

Hypothermia: MedlinePlus Medical Encyclopedia. Last reviewed November 13, 2021. Accessed November 21, 2023.

Body temperature norms: MedlinePlus Medical Encyclopedia. Published 2017.Accessed November 21, 2023.

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Emilie White, PharmD

Clinical Pharmacist and Medical Blogger

Emilie White, PharmD is a clinical pharmacist with over a decade of providing direct patient care to those hospitalized. She received her Doctor of Pharmacy degree from Massachusetts College of Pharmacy and Health Sciences. After graduation, Emilie completed a postgraduate pharmacy residency at Bon Secours Memorial Regional Medical Center in Virginia. Her background includes caring for critical care, internal medicine, and surgical patients.

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