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*[[Thyroid hormone]] plays an important role in cellular [[metabolism]].
*[[Thyroid hormone]] plays an important role in cellular [[metabolism]].
*Long-standing [[hypothyroidism]] is associated with reduced [[metabolic rate]] and decreased [[oxygen]] consumption, which affects all [[organ systems]].
*Long-standing [[hypothyroidism]] is associated with reduced [[metabolic rate]] and decreased [[oxygen]] consumption, which affects all [[organ systems]].
*Reduced metabolism results in [[hypothermia]].
*Reduced [[metabolism]] results in [[hypothermia]].
*Reduced metabolism and decreased oxygen also results in decreased drug metabolism leading to overdosing of medications particularly sedatives, hypnotics, and anesthetic agents; this can precipitate myxedema coma.
*Reduced [[metabolism]] and decreased [[oxygen]] also results in decreased drug metabolism leading to overdosing of [[medications]] particularly [[sedatives]], [[hypnotics]], and [[anesthetic agents]]; this can precipitate myxedema coma.
*Even in severe hypothyroidism a balance of metabolic homeostasis is achieved through adaptive neurovascular mechanisms. However in conditions such as respiratory or urinary tract infections, cardiac, acute myocardial infarction or stroke interfere with this adaptive mechanisms by decreasing the blood volume and ventilation triggering myxedema coma.
*Even in severe [[hypothyroidism]] a balance of metabolic homeostasis is achieved through adaptive neurovascular mechanisms. However in conditions such as [[respiratory]] or [[urinary tract infections]], [[cardiac]], [[acute myocardial infarction]] or [[stroke]] interfere with this adaptive mechanisms by decreasing the [[blood volume]] and [[ventilation]] triggering myxedema coma.
{{familytree/start}}{{familytree | | | | | | | | | A01 | | | | | |A01=[[Hypothyroidism]]}}
{{familytree/start}}{{familytree | | | | | | | | | A01 | | | | | |A01=[[Hypothyroidism]]}}
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Revision as of 18:56, 19 October 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Overview

Myxedema coma occurs as a result of long-standing, un-diagnosed, or untreated hypothyroidism and is usually precipitated by a systemic illness. Thyroid hormone plays an important role in celluar metabolism. Long-standing hypothyroidism results in reduced metabolic rate and decreased oxygen consumption, which affects all organ systems. Reduced metabolism and decreased oxygen results in hypothermia and decreased drug metabolism leading to overdosing of medications particularly sedatives, hypnotics, and anesthetic agents and can precipitate myxedema coma.

Pathophysiology

  • Myxedema coma occurs as a result of long-standing, undiagnosed, or untreated hypothyroidism.[1][2][3][4]
  • Myxedema coma is usually precipitated by a systemic illness.

Triggers

Pathogenesis

 
 
 
 
 
 
 
 
Hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Precipitating Factor
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
T4
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
↓ IntracellularT3
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hypothalamus
 
Respiratory
 
 
 
Cardiovascluar
 
Renal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Thermogenesis
 
Hypercapnia
Hypoxia
 
 
 
Inotropic
Bradycardia
 
↓ Volume status
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hypothermia
 
Hypoventilation
 
 
 
Cardiac output
Blood volume
 
GFR
↑ ADH
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alteration of mental state
 
Cerebral anoxia
 
 
 
↓Arterial pressure/shock
 
Hyponatremia
Edema
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Myxedema Coma
 
 
 
 
 
 

The following table summarizes the various effects of reduced thyroid hormone on different organ systems

Organ System Effect due to Decreased Thyroid Hormone Manifestation
Cardiovascular
Neurologic
  • Altered brain function due to
    • Reduced oxygen delivery and consumption
    • Decreased glucose utilization
    • Reduced cerebral blood flow.
  • Altered consciousness
Pulmonary
Renal
Gastrointestinal
Hematologic

Associated Conditions

Common conditions associated with myxedema coma include:

References

  1. Rizzo L, Mana DL, Bruno OD, Wartofsky L (2017). "[Myxedema coma]". Medicina (B Aires) (in Spanish; Castilian). 77 (4): 321–328. PMID 28825577. Vancouver style error: initials (help)
  2. Wall CR (2000). "Myxedema coma: diagnosis and treatment". Am Fam Physician. 62 (11): 2485–90. PMID 11130234.
  3. Mathew V, Misgar RA, Ghosh S, Mukhopadhyay P, Roychowdhury P, Pandit K, Mukhopadhyay S, Chowdhury S (2011). "Myxedema coma: a new look into an old crisis". J Thyroid Res. 2011: 493462. doi:10.4061/2011/493462. PMC 3175396. PMID 21941682.
  4. Wartofsky L (2006). "Myxedema coma". Endocrinol. Metab. Clin. North Am. 35 (4): 687–98, vii–viii. doi:10.1016/j.ecl.2006.09.003. PMID 17127141.