Dec 31, 2018


Myxedema Coma| definition, causes, symptoms, diagnosis and treatment

Definition: The term myxedema coma is a misnomer, as myxedema and coma are neither diagnostic criteria nor common presenting findings. A more proper description would be critical hypothyroidism.

Precipitating factors

  • Infections, especially pneumonia, are perhaps the most common precipitating factor.
  • Cardiac events (myocardial infarction, congestive heart failure).
  • Cerebral infarction.
  • Trauma, hemorrhage.
    myxedema-coma
  • Hypothermia, hypoglycemia.
  • Respiratory depression secondary to anesthetics or sedatives.

Clinical findings/ picture

  • Hypothermia
  • Hypotension
  • Bradycardia
  • Mental status depression ( common clinical feature and may progress to stupor or frank coma
  • Hypoglycemia
  • Generalized skin and soft tissue swelling and the presence of cool, dry skin.
  • Periorbital edema , ptosis, macroglossia

Confirmation:

  • The diagnosis is suspected clinically and confirmed with TFT (elevated TSH levels and low levels of free T4 and T3)
  • The degree of TFT abnormalities does not distinguish hypothyroidism from myxedema coma. Rather, the distinction is based on clinical findings. 
  • It is important for the clinician to be able to differentiate hypothyroidism from euthyroid sick syndrome, in which patients have a reduction in both TSH and thyroid hormone levels.

Treatment of Myxedema Coma

  • Thyroid hormone replacement should be given intravenously to ensure rapid restoration of bioactive thyroxine levels and resolution of symptoms
  • High-dose intravenous thyroxine is given as a bolus of 300-500 mcg, followed by 50-100 mcg daily depending on the patient's age, weight, and risk of complications. This method provides a more rapid recovery of symptoms but carries the potential for unwanted cardiac events resulting from the rapid replacement of thyroxine.
  • In the low-dose method, thyroxine 25 mcg is given daily for 1 week followed by a gradually increased dose until the patient is able to resume normal thyroxine orally
  • Regardless of the replacement method used, all patients should be continuously monitored for hypertension and cardiac ischemia.
  • Supportive care should be provided while thyroid hormone levels are replaced. Ventilatory support, passive external rewarming, and correction of underlying electrolyte abnormalities are commonly required. 

About Author

Tamer Mobarak, E.N.T resident at Qasr-Elainy teaching hospital, Cairo university.


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