Myxedema coma

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Myxedema coma
Specialty Endocrinology   OOjs UI icon edit-ltr-progressive.svg
Symptoms deterioration of the patient's mental status [1]
Causesinfections (especially pneumonia and urosepsis), certain medications, failure to reinstate thyroid replacement therapy [1]
Treatmentadmission to the intensive care unit, correct hypovolemia and electrolyte abnormalities, mechanical ventilation if needed, thyroid hormone replacement [1]

Myxedema coma is an extreme or decompensated form of hypothyroidism and while uncommon, is potentially lethal. [1] [2] [3] A person may have laboratory values identical to a "normal" hypothyroid state, but a stressful event (such as an infection, myocardial infarction, or stroke) precipitates the myxedema coma state, usually in the elderly. Primary symptoms of myxedema coma are altered mental status and low body temperature. Low blood sugar, low blood pressure, hyponatremia, hypercapnia, hypoxia, slowed heart rate, and hypoventilation may also occur. [4] Myxedema, although included in the name, is not necessarily seen in myxedema coma.[ citation needed ] Coma is also not necessarily seen in myxedema coma, [5] as patients may be obtunded without being comatose. [2]

Contents

According to newer theories, myxedema coma could result from allostatic overload in a situation where the effects of hypothyroidism are amplified by nonthyroidal illness syndrome. [6]

Causes

Myxedema coma represents an extreme or decompensated form of hypothyroidism. Most cases occur in patients who have been previously diagnosed with hypothyroidism, yet in some cases, hypothyroidism may not have been previously identified. [1] [2] [3]

Common precipitating factors of myxedema coma include:

Other precipitating factors include:

Pathophysiology

The thyroid gland is responsible for regulating whole-body metabolism through the production of two major hormones: thyroxine (T4) and triiodothyronine (T3). Of the metabolically active thyroid hormones, 93% is T4 and 7% is T3. T3 is four times more potent than T4 and most T4 is converted to T3 in the tissues. Iodine is necessary for adequate hormone production. Thyroid-stimulating hormone (TSH) is a circulating or serum hormone from the pituitary gland that stimulates the thyroid gland to produce T3 and T4. Hypothyroidism occurs when the thyroid gland does not produce enough T3 and T4. [3]

The most common cause of hypothyroidism worldwide is too little dietary iodine. Hashimoto's thyroiditis is the most common cause of hypothyroidism in countries with sufficient dietary iodine. With the cessation of the production of thyroid hormone, the thyroid gland contains enough reserve T3 and T4 to last 2 to 3 months. [3]

The thyroid hormones T3 and T4 influence the production by virtually all cells in the body of hundreds of new intracellular proteins and enzymes. This influence includes the expression of the calcium ATPase, regulation of ion channels, oxidative phosphorylation, increased Na-K-ATPase activity, increased carbohydrate metabolism, increased free fatty acids, increased vitamin requirements, and increased overall metabolism. The absence of the thyroid hormones T3 and T4 are responsible for many bodily functions at the genetic and cellular level and an absence of these thyroid hormones as seen in myxedema coma has very serious consequences including a broad spectrum of symptoms and a high mortality rate. [3]

Diagnosis

Clinical features of myxedema coma: [1] [2] [3]

Laboratory features in myxedema coma: [1] [2] [3]

Epidemiology

Hypothyroidism is four times more common in women than men. The incidence of myxedema coma has been reported to be 0.22 per 1000000 per year but the data is limited and especially lacking in countries outside the western world and countries along the equator. Myxedema coma is most common in people 60 years old and older and is most common in the winter months when hypothermia is more common. [1] [2] [3]

See also

Related Research Articles

<span class="mw-page-title-main">Hyperthyroidism</span> Thyroid gland disease that involves an overproduction of thyroid hormone

Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. Some, however, use the terms interchangeably. Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, hand tremor, and weight loss. Symptoms are typically less severe in the elderly and during pregnancy. An uncommon but life-threatening complication is thyroid storm in which an event such as an infection results in worsening symptoms such as confusion and a high temperature; this often results in death. The opposite is hypothyroidism, when the thyroid gland does not make enough thyroid hormone.

<span class="mw-page-title-main">Thyroid</span> Endocrine gland in the neck; secretes hormones that influence metabolism

The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the isthmus (PL: isthmi). The thyroid gland is a butterfly-shaped gland located in the neck below the Adam's apple. Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid. The thyroid gland secretes three hormones: the two thyroid hormones – triiodothyronine (T3) and thyroxine (T4) – and a peptide hormone, calcitonin. The thyroid hormones influence the metabolic rate and protein synthesis and growth and development in children. Calcitonin plays a role in calcium homeostasis. Secretion of the two thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which is secreted from the anterior pituitary gland. TSH is regulated by thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus.

<span class="mw-page-title-main">Graves' disease</span> Autoimmune endocrine disease

Graves' disease, also known as toxic diffuse goiter, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyroid. Signs and symptoms of hyperthyroidism may include irritability, muscle weakness, sleeping problems, a fast heartbeat, poor tolerance of heat, diarrhea and unintentional weight loss. Other symptoms may include thickening of the skin on the shins, known as pretibial myxedema, and eye bulging, a condition caused by Graves' ophthalmopathy. About 25 to 30% of people with the condition develop eye problems.

<span class="mw-page-title-main">Hypothyroidism</span> Endocrine disease

Hypothyroidism is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as poor ability to tolerate cold, a feeling of tiredness, constipation, slow heart rate, depression, and weight gain. Occasionally there may be swelling of the front part of the neck due to goitre. Untreated cases of hypothyroidism during pregnancy can lead to delays in growth and intellectual development in the baby or congenital iodine deficiency syndrome.

<span class="mw-page-title-main">Iodothyronine deiodinase</span> Class of enzymes

Iodothyronine deiodinases (EC 1.21.99.4 and EC 1.21.99.3) are a subfamily of deiodinase enzymes important in the activation and deactivation of thyroid hormones. Thyroxine (T4), the precursor of 3,5,3'-triiodothyronine (T3) is transformed into T3 by deiodinase activity. T3, through binding a nuclear thyroid hormone receptor, influences the expression of genes in practically every vertebrate cell. Iodothyronine deiodinases are unusual in that these enzymes contain selenium, in the form of an otherwise rare amino acid selenocysteine.

<span class="mw-page-title-main">Congenital hypothyroidism</span> Medical condition

Congenital hypothyroidism (CH) is thyroid hormone deficiency present at birth. If untreated for several months after birth, severe congenital hypothyroidism can lead to growth failure and permanent intellectual disability. Infants born with congenital hypothyroidism may show no effects, or may display mild effects that often go unrecognized as a problem. Significant deficiency may cause excessive sleeping, reduced interest in nursing, poor muscle tone, low or hoarse cry, infrequent bowel movements, significant jaundice, and low body temperature.

Thyroid-stimulating hormone (also known as thyrotropin, thyrotropic hormone, or abbreviated TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3) which stimulates the metabolism of almost every tissue in the body. It is a glycoprotein hormone produced by thyrotrope cells in the anterior pituitary gland, which regulates the endocrine function of the thyroid.

<span class="mw-page-title-main">Myxedema</span> Medical condition

Myxedema is a term used synonymously with severe hypothyroidism. However, the term is also used to describe a dermatological change that can occur in hypothyroidism and (rare) paradoxical cases of hyperthyroidism. In this latter sense, myxedema refers to deposition of mucopolysaccharides in the dermis, which results in swelling of the affected area. One manifestation of myxedema occurring in the lower limb is pretibial myxedema, a hallmark of Graves disease, an autoimmune form of hyperthyroidism. Myxedema can also occur in Hashimoto thyroiditis and other long-standing forms of hypothyroidism.

<span class="mw-page-title-main">Hashimoto's thyroiditis</span> Autoimmune disease

Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis and Hashimoto's disease, is an autoimmune disease in which the thyroid gland is gradually destroyed. A slightly broader term is autoimmune thyroiditis, identical other than that it is also used to describe a similar condition without a goitre.

<span class="mw-page-title-main">Levothyroxine</span> Thyroid hormone

Levothyroxine, also known as L-thyroxine, is a synthetic form of the thyroid hormone thyroxine (T4). It is used to treat thyroid hormone deficiency (hypothyroidism), including a severe form known as myxedema coma. It may also be used to treat and prevent certain types of thyroid tumors. It is not indicated for weight loss. Levothyroxine is taken orally (by mouth) or given by intravenous injection. Levothyroxine has a half-life of 7.5 days when taken daily, so about six weeks is required for it to reach a steady level in the blood.

Myxedema psychosis is a relatively uncommon consequence of hypothyroidism, such as in Hashimoto's thyroiditis or in patients who have had the thyroid surgically removed and are not taking thyroxine. A chronically under-active thyroid can lead to slowly progressive dementia, delirium, and in extreme cases to hallucinations, coma, or psychosis, particularly in the elderly.

<span class="mw-page-title-main">Thyroid disease</span> Medical condition

Thyroid disease is a medical condition that affects the function of the thyroid gland. The thyroid gland is located at the front of the neck and produces thyroid hormones that travel through the blood to help regulate many other organs, meaning that it is an endocrine organ. These hormones normally act in the body to regulate energy use, infant development, and childhood development.

Thyroid storm is a rare but severe and life-threatening complication of hyperthyroidism. It occurs when overactive thyroid activity leads to hypermetabolism, the end result being death from cardiac arrest or multiple organ failure.

<span class="mw-page-title-main">Liothyronine</span> Chemical compound

Liothyronine is a manufactured form of the thyroid hormone triiodothyronine (T3). It is most commonly used to treat hypothyroidism and myxedema coma. It can be taken by mouth or by injection into a vein.

Thyroid function tests (TFTs) is a collective term for blood tests used to check the function of the thyroid. TFTs may be requested if a patient is thought to suffer from hyperthyroidism or hypothyroidism, or to monitor the effectiveness of either thyroid-suppression or hormone replacement therapy. It is also requested routinely in conditions linked to thyroid disease, such as atrial fibrillation and anxiety disorder.

Desiccated thyroid, also known as thyroid extract, is thyroid gland that has been dried and powdered for medical use. It is used to treat hypothyroidism. It is less preferred than levothyroxine. It is taken by mouth. Maximal effects may take up to three weeks to occur.

<span class="mw-page-title-main">Reverse triiodothyronine</span> Chemical compound

Reverse triiodothyronine (3,3′,5′-triiodothyronine, reverse T3, or rT3) is an isomer of triiodothyronine (3,5,3′ triiodothyronine, T3).

An antithyroid agent is a hormone inhibitor acting upon thyroid hormones.

Euthyroid sick syndrome (ESS) is a state of adaptation or dysregulation of thyrotropic feedback control wherein the levels of T3 and/or T4 are abnormal, but the thyroid gland does not appear to be dysfunctional. This condition may result from allostatic responses of hypothalamus-pituitary-thyroid feedback control, dyshomeostatic disorders, drug interferences, and impaired assay characteristics in critical illness.

<span class="mw-page-title-main">Thyroid hormones</span> Hormones produced by the thyroid gland

Thyroid hormones are any hormones produced and released by the thyroid gland, namely triiodothyronine (T3) and thyroxine (T4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine, derived from food. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre.

References

  1. 1 2 3 4 5 6 7 8 Wall, Cristen Rhodes (2000-12-01). "Myxedema Coma: Diagnosis and Treatment". American Family Physician. 62 (11): 2485–2490. ISSN   0002-838X. PMID   11130234.
  2. 1 2 3 4 5 6 Mathew, Vivek; Misgar, Raiz Ahmad; Ghosh, Sujoy; Mukhopadhyay, Pradip; Roychowdhury, Pradip; Pandit, Kaushik; Mukhopadhyay, Satinath; Chowdhury, Subhankar (2011-09-15). "Myxedema Coma: A New Look into an Old Crisis". Journal of Thyroid Research. 2011: 493462. doi: 10.4061/2011/493462 . PMC   3175396 . PMID   21941682.
  3. 1 2 3 4 5 6 7 8 Elshimy, Ghada; Correa, Ricardo (2022). "Myxedema". StatPearls. StatPearls Publishing. PMID   31424777.
  4. ↑ Van den Berghe, Greet, ed. (2008). Acute endocrinology: From Cause to Consequence (1 ed.). New York: Humana Press. pp.  29–44. ISBN   978-1-60327-176-9.
  5. ↑ Gardner, David G., Shoback, Dolores M., Greenspan, Francis S. (2017). Greenspan's basic & clinical endocrinology (10th ed.). McGraw-Hill Education. p. 783. ISBN   978-1259589294. OCLC   1075522289.{{cite book}}: CS1 maint: multiple names: authors list (link)
  6. ↑ Chatzitomaris, Apostolos; Hoermann, Rudolf; Midgley, John E.; Hering, Steffen; Urban, Aline; Dietrich, Barbara; Abood, Assjana; Klein, Harald H.; Dietrich, Johannes W. (20 July 2017). "Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming". Frontiers in Endocrinology. 8: 163. doi: 10.3389/fendo.2017.00163 . PMC   5517413 . PMID   28775711.
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