Myxoedema Coma

Introduction

Myxoedema coma is a life-threatening complication of hypothyroidism.
It follows a background of long-standing
hypothyroidism.

Clinical features of myxoedema coma

Myxoedema coma may be precipitated by exposure to cold, infection, trauma and central nervous system suppressants

  1. Coma with extreme hypothermia,
    temperatures 24 – 32ºC
  2. Seizures
  3. Areflexia
  4. CO retention and respiratory depression due to decreased cerebral blood flow

Differential diagnoses

  • Coma due to CNS depressants
  • Adrenal insufficiency
  • Morbid depression

Complications of myxoedema coma

  1. Cardiac failure
  2. Respiratory failure
  3. Death

Investigations

  • T3 (triiodothyronine) assay
  • T4 (thyroxine) assay
  • Thyroid stimulating hormone (TSH) assay

Treatment for myxoedema coma

Treatment objectives

  1. To restore normal body metabolism
  2. To prevent death

Drug treatment

  • Triiodothyronine 20 µg
    intravenously stat,

    • then 20  micrograms every 8 hours until there is sustained clinical improvement
  • May also require hydrocortisone 100 mg intravenously every 8 hours
  • Maintain therapy with oral thyroxine in a dose of 50 µg per day
  • Treat precipitating factor(s)

Precaution

  • Patients should not be re-warmed rapidly because of risk of cardiac arrhythmias