Myxedema

Myxedema
Myxoedema
Classification and external resources

Hyaluronan, an example of a mucopolysaccharide.
ICD-10 E03.9
ICD-9 244.9
DiseasesDB 6558
MedlinePlus 000353
eMedicine med/1581 derm/347
MeSH D009230

Myxedema (British English: myxoedema) describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components (like glycosaminoglycans, hyaluronic acid, and other mucopolysaccharides) in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease.[1]:535 It is more common in women than in men. [2]

Contents

Terminology

The word originates from μύξα, taken from ancient Greek to convey 'mucus' or 'slimy substance' and ὁίδημα for swelling.

Myxedema coma is rare and establishing the diagnosis requires a high index of suspicion. Myxedema coma represents the severest form of hypothyroidism and has an associated mortality rate of 30 percent to 40 percent. It can occur due to long-standing, untreated hypothyroidism, but is often linked to a precipitant, such as acute infection, myocardial infarction, congestive heart failure, cerebral vascular accident, trauma, or drug toxicity. Several medications can cause hypothyroidism, and patients taking them must be carefully monitored. These medications include amiodarone, lithium, and sedatives. No consensus exists on specific thyroid hormone replacement regimens for myxedema coma. Most experts agree that a large intravenous bolus of levothyroxine should be administered (200 to 400 mcg), followed by daily doses of 50 to 100 mcg, based on the patient's weight and comorbidities. Other experts advocate the use of triiodothyronine (T3) or a combination of both T3 and T4. In addition to thyroid replacement therapy, it is important to detect coexisting adrenal insufficiency and treat patients with stress-dose steroids to avoid precipitating adrenal crisis.[5]

Cause

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

  • Exophthalmos in particular results from TSH receptor stimulation on fibroblasts behind the eyes which leads to increased glycosaminoglycan deposition. It is thought that many cells responsible for forming connective tissue react to increases in TSH levels.[citation needed]
  • Secondarily, in autoimmune thyroid diseases lymphocytes react to the TSH receptor. Thus, in addition to the inflammation within the thyroid, any cell that expresses the TSH receptor will likely experience lymphocytic infiltrates as well. The inflammation can cause tissue damage and scar tissue formation, explaining the deposition of glycosaminoglycans.[citation needed]

The increased deposition of glycosaminoglycans causes an osmotic edema and fluid collection.

Hashimoto's thyroiditis is the most common cause of myxedema in the United States.[6]

See also

References

  1. ^ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0. 
  2. ^ BRS Pathology - A.S. Schneider, P.A. Szanto - 3rd edition - page 314
  3. ^ "Pretibial Myxedema", Retrieved on 2009-3-27
  4. ^ "myxedema" at Dorland's Medical Dictionary
  5. ^ 1.Ross D. Myxedema Coma. UpToDate.com. Last update: September 9, 2009. Available at: http://www.uptodate.com/patients/content/topic.do?topicKey=~aqassDt4J0HGlq. Date accessed: Jan 20, 2010.
  6. ^ "Hasihimotos Thyroiditis", Retrieved on 2009-3-27

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Look at other dictionaries:

  • myxedema — n. (Med.) A pathological condition due to severe hyperthyroidism, marked by dry skin and swellings around lips and nose as well as mental and physical deterioration. [Also spelled {myx[oe]dema}.] [WordNet 1.5 +PJC] …   The Collaborative International Dictionary of English

  • myxedema — [mik΄sə dē′mə] n. [ModL: see MYXO & EDEMA] a disease caused by failure of the thyroid gland and characterized by a drying and thickening of the skin and a slowing down of physical and mental activity myxedematous [mik΄sə dē′mətəs] adj …   English World dictionary

  • myxedema — myxedematous /mik si dem euh teuhs, dee meuh /, adj. myxedemic /mik si dem ik/, adj. /mik si dee meuh/, n. Pathol. a condition characterized by thickening of the skin, blunting of the senses and intellect, and labored speech, associated with… …   Universalium

  • myxedema — Myxoedema Myx [oe]*de ma, n. [NL. fr. Gr. ? mucus + [oe]dema.] (Med.) A disease producing a peculiar cretinoid appearance of the face, slow speech, and dullness of intellect, and due to failure of the functions of the thyroid gland. [Also spelled …   The Collaborative International Dictionary of English

  • myxedema — Hypothyroidism characterized by a relatively hard edema of subcutaneous tissue, with increased content of mucins (proteoglycans) in the fluid; characterized by somnolence, slow mentation, dryness and loss of hair, increased fluid in …   Medical dictionary

  • Myxedema coma — Classification and external resources ICD 10 E03.5 Myxedema coma is state of decompensated hypothyroidism. The patient may have lab values identical to a normal hypothyroid state, but a stressful event (infections, MI, CVA, drugs, etc.)… …   Wikipedia

  • Myxedema, infantile — Hypothyroidism (subnormal activity of the thyroid gland) that starts after birth and is manifest by features including delays in growth and development and myxedema surfacing during infancy. Myxedema is a dry waxy type of swelling, often with… …   Medical dictionary

  • myxedema madness — psychiatric disturbances resulting from hypothyroidism and myxedema, ranging from mental slowness and loss of memory to agitation and psychosis …   Medical dictionary

  • myxedema — noun Etymology: New Latin, from Greek myxa lamp wick, nasal mucus + New Latin edema edema more at mucus Date: 1877 severe hypothyroidism characterized by firm inelastic edema, dry skin and hair, and loss of mental and physical vigor •… …   New Collegiate Dictionary

  • myxedema — noun A form of cutaneous and dermal edema that is secondary to increased deposition of connective tissue components in subcutaneous tissue …   Wiktionary

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