Myxedema

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Myxedema
Other namesMyxoedema
Hyaluronan.svg
Hyaluronan, an example of a mucopolysaccharide
Specialty Endocrinology

Myxedema (British English : myxoedema) 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.

Contents

Etymology

The word myxedema originates from Greek : grc, meaning "mucus" or "slimy substance", and οἴδημα for "swelling".

Signs and symptoms

Myxedema face.png
Man with myxedema or severe hypothyroidism showing an expressionless face, puffiness around the eyes and pallor
Myxedema standing.png
Additional findings include swelling of the arms and legs and significant ascites.
Woman with myxedema, Bulgaria, 1930s. BASA-3K-7-529-35(7)-Myxedema.jpg
Woman with myxedema, Bulgaria, 1930s.

Myxedema's characteristic physical sign is non-pitting edema, in contrast to pitting edema. [1]

Myxedema can also occur in the lower leg (pretibial myxedema) and behind the eyes (exophthalmos).

Severe cases, requiring hospitalization can exhibit signs of hypothermia, hypoglycemia, hypotension, respiratory depression, and coma.

Causes

Myxedema is known to occur in various forms of hypothyroidism, as well as hyperthyroidism, including Graves disease. One of the hallmarks of Grave's disease is pretibial myxedema, myxedema of the lower limb. [2]

Myxedema is more common in women than in men. [3]

Myxedema can occur in:

Pathophysiology

Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components. The connective fibres are separated by an increased amount of protein and mucopolysaccharides. These can include glycosaminoglycans, such as hyaluronic acid, chondroitin sulfate and other mucopolysaccharides. [2] This protein-mucopolysaccharide complex binds water, producing non-pitting boggy edema, in particular around eyes, hands, feet and in the supraclavicular fossae. Myxoedema is responsible for the thickening of the tongue and the laryngeal and pharyngeal mucous membranes, which results in thick slurred speech and hoarseness, both of which are seen commonly in hypothyroidism.

The increased deposition of glycosaminoglycan is not fully understood, however, two mechanisms predominate:

Diagnosis

It is often possible to diagnose myxedema on clinical grounds alone. Characteristic symptoms are weakness, cold intolerance, mental and physical slowness, dry skin, typical facies, and hoarse voice. Results of the total serum thyroxine and free thyroxine index tests usually will confirm the diagnosis. [9]

Management

Primary treatment is prompted by the administration of adequate doses of either the thyroid hormone L-thyroxine given intravenously or by giving liothyronine via a nasogastric tube. It is essential to identify and treat the condition precipitating the coma. [9]

Myxedema coma is rare but often fatal. It occurs most often in elderly women and may be mistaken for one of the chronic debilitating diseases common to this age group. [9]

Though the exact cause of myxedema is still unclear, a wealth of research has demonstrated the importance of iodine. [10] In an important study [11] the researchers showed that in the myxedematous type of cretinism treatment with iodine normalizes thyroid function provided that the treatment is begun early in the postnatal period. If not, the prognosis remains dismal. [10]

History

Myxedema was first treated successfully in 1891 when George Redmayne Murray diagnosed a 46-year-old woman with the disease. He prescribed an extract from sheep thyroid. The patient improved significantly within a few weeks and lived another 28 years while taking the sheep thyroid extract. [12]

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 hormones. 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.

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">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.

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.

<span class="mw-page-title-main">Toxic multinodular goitre</span> Medical condition

Toxic multinodular goiter (TMNG), also known as multinodular toxic goiter (MNTG), is an active multinodular goiter associated with hyperthyroidism.

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

Pretibial myxedema is an infiltrative dermopathy, resulting as a rare complication of Graves' disease, with an incidence rate of about 1–5%.

<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.

<span class="mw-page-title-main">De Quervain's thyroiditis</span> Medical condition

De Quervain's thyroiditis, also known as subacute granulomatous thyroiditis or giant cell thyroiditis, is a member of the group of thyroiditis conditions known as resolving thyroiditis. People of all ages and genders may be affected.

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">Thyrotropin receptor</span> Mammalian protein found in Homo sapiens

The thyrotropin receptor is a receptor that responds to thyroid-stimulating hormone and stimulates the production of thyroxine (T4) and triiodothyronine (T3). The TSH receptor is a member of the G protein-coupled receptor superfamily of integral membrane proteins and is coupled to the Gs protein.

<span class="mw-page-title-main">Graves' ophthalmopathy</span> Medical condition

Graves’ ophthalmopathy, also known as thyroid eye disease (TED), is an autoimmune inflammatory disorder of the orbit and periorbital tissues, characterized by upper eyelid retraction, lid lag, swelling, redness (erythema), conjunctivitis, and bulging eyes (exophthalmos). It occurs most commonly in individuals with Graves' disease, and less commonly in individuals with Hashimoto's thyroiditis, or in those who are euthyroid.

Postpartum thyroiditis refers to thyroid dysfunction occurring in the first 12 months after pregnancy and may involve hyperthyroidism, hypothyroidism or the two sequentially. According to the National Institute of Health, postpartum thyroiditis affects about 8% of pregnancies. There are, however, different rates reported globally. This is likely due to the differing amounts of average postpartum follow times around the world, and due to humans' own innate differences. For example, in Bangkok, Thailand the rate is 1.1%, but in Brazil it is 13.3%. The first phase is typically hyperthyroidism. Then, the thyroid either returns to normal or a woman develops hypothyroidism. Of those women who experience hypothyroidism associated with postpartum thyroiditis, one in five will develop permanent hypothyroidism requiring lifelong treatment.

Myxedema coma is an extreme or decompensated form of hypothyroidism and while uncommon, is potentially lethal. A person may have laboratory values identical to a "normal" hypothyroid state, but a stressful event 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. Myxedema, although included in the name, is not necessarily seen in myxedema coma. Coma is also not necessarily seen in myxedema coma, as patients may be obtunded without being comatose.

<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.

Thyroid disease in pregnancy can affect the health of the mother as well as the child before and after delivery. Thyroid disorders are prevalent in women of child-bearing age and for this reason commonly present as a pre-existing disease in pregnancy, or after childbirth. Uncorrected thyroid dysfunction in pregnancy has adverse effects on fetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect neurointellectual development in the early life of the child. Due to an increase in thyroxine binding globulin, an increase in placental type 3 deioidinase and the placental transfer of maternal thyroxine to the fetus, the demand for thyroid hormones is increased during pregnancy. The necessary increase in thyroid hormone production is facilitated by high human chorionic gonadotropin (hCG) concentrations, which bind the TSH receptor and stimulate the maternal thyroid to increase maternal thyroid hormone concentrations by roughly 50%. If the necessary increase in thyroid function cannot be met, this may cause a previously unnoticed (mild) thyroid disorder to worsen and become evident as gestational thyroid disease. Currently, there is not enough evidence to suggest that screening for thyroid dysfunction is beneficial, especially since treatment thyroid hormone supplementation may come with a risk of overtreatment. After women give birth, about 5% develop postpartum thyroiditis which can occur up to nine months afterwards. This is characterized by a short period of hyperthyroidism followed by a period of hypothyroidism; 20–40% remain permanently hypothyroid.

Antithyroid autoantibodies (or simply antithyroid antibodies) are autoantibodies targeted against one or more components on the thyroid. The most clinically relevant anti-thyroid autoantibodies are anti-thyroid peroxidase antibodies (anti-TPO antibodies, TPOAb), thyrotropin receptor antibodies (TRAb) and thyroglobulin antibodies (TgAb). TRAb's are subdivided into activating, blocking and neutral antibodies, depending on their effect on the TSH receptor. Anti-sodium/iodide (Anti–Na+/I−) symporter antibodies are a more recent discovery and their clinical relevance is still unknown. Graves' disease and Hashimoto's thyroiditis are commonly associated with the presence of anti-thyroid autoantibodies. Although there is overlap, anti-TPO antibodies are most commonly associated with Hashimoto's thyroiditis and activating TRAb's are most commonly associated with Graves' disease. Thyroid microsomal antibodies were a group of anti-thyroid antibodies; they were renamed after the identification of their target antigen (TPO).

References

  1. ↑ Bhutada, Abhishek S.; Kodankandath, Thomas V. (July 2022). "Clinical Manifestations of Severe Untreated Hypothyroidism". Cureus. 14 (7): e26595. doi: 10.7759/cureus.26595 . ISSN   2168-8184. PMC   9354917 . PMID   35936163.
  2. 1 2 Berger, William D. James, Dirk M. Elston, Timothy G. (2011). Andrews' Diseases of the skin : clinical dermatology (11th ed.). [London]: Saunders/ Elsevier. ISBN   978-1-4377-0314-6.{{cite book}}: CS1 maint: multiple names: authors list (link)
  3. ↑ Schneider, Arthur S.; Kim, Philip A. Szanto; with special contributions by Sandra I.; Swanson, Todd A. (2009). Pathology (4th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. pp.  314. ISBN   978-1451109061.
  4. ↑ "Pretibial Myxedema". Archived from the original on 2016-03-04. Retrieved 2009-03-27.
  5. ↑ "Hypothyroidism". The Lecturio Medical Concept Library. Retrieved 27 July 2021.
  6. ↑ "Fibroblast". Genetics Home Reference. U.S. National Library of Medicine. 2014-05-05. Retrieved 2014-05-10.
  7. ↑ "Fibroblasts" . Retrieved 16 August 2018.
  8. ↑ "Lymphocytes". The Lecturio Medical Concept Library. Retrieved 27 July 2021.
  9. 1 2 3 McConahey, W. M. (March 1978). "Diagnosing and treating myxedema and myxedema coma". Geriatrics. 33 (3): 61–66. ISSN   0016-867X. PMID   624451.
  10. 1 2 Lindholm, J.; Laurberg, P. (2011). "Hypothyroidism and Thyroid Substitution: Historical Aspects". Journal of Thyroid Research. 2011: 809341. doi: 10.4061/2011/809341 . PMC   3134382 . PMID   21760981.
  11. ↑ Vanderpas, Jean B.; Rivera-Vanderpas, Maria T.; Bourdoux, Pierre; Luvivila, Kapata; Lagasse, Raphael; Perlmutter-Cremer, Noémi; Delange, François; Lanoie, Leo; Ermans, André M. (1986-09-25). "Reversibility of Severe Hypothyroidism with Supplementary Iodine in Patients with Endemic Cretinism". New England Journal of Medicine. 315 (13): 791–795. doi:10.1056/NEJM198609253151302. ISSN   0028-4793. PMID   3018564.
  12. ↑ "Eating Organs to Cure Disease". Tacomed.com. Archived from the original on 6 September 2017. Retrieved 15 June 2017.
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