Overview
Myxoedema coma is an extreme, decompensated form of hypothyroidism. In this case, decompensation describes the inability of the body to adapt to untreated hypothyroidism.
To help make sense of this chapter, it may be helpful to refer to Endocrine and Metabolic Physiology.
Epidemiology
- More common in women
- Incidence is highest >60 years of age
- Usually seen in patients with long-standing hypothyroidism
Risk Factors
- Hypothermia
- Infection (e.g. pneumonia)
- Some drugs (amiodarone, beta-blockers, anaesthesia, lithium)
- Hypoglycaemia
- Stroke
- Surgery or trauma
- Burns
- Hypoxia
Presentation
Myxoedema coma can be difficult to diagnose. It usually presents with confusion and hypothermia. Features may be:
- Acute mental state changes (e.g. confusion) – common
- Hypothermia (<35.5°C often)
- Generalised swelling and puffiness due to oedema
- Coarse hair
- Dry skin
- Bradycardia
- Bradypnoea
- Hypoxia
Investigations
- TFTs:
- TSH: usually raised
- T3 and T4: usually reduced
- FBC:
- May show signs of infection (e.g. raised white cell count)
- U&Es:
- May show hyponatraemia
- Blood glucose:
- May be reduced
- Serum cortisol:
- To rule out adrenal insufficiency which may co-exist with hypothyroidism in hypopituitarism
- ABGs:
- May show hypoxia, hypercapnia, and respiratory acidosis
- ECG:
- May show bradycardia
Management
- 1st-line: IV fluids + IV thyroid hormone replacement + IV hydrocortisone (until the possibility of coexisting adrenal insufficiency has been ruled out)
- Correct hypoglycaemia and electrolyte disturbances
- Consider non-invasive ventilation or intubation and ventilation
Complications and Prognosis
Complications
- Myocardial infarction
- Arrhythmia
- Adrenal crisis
Prognosis
- Mortality rate is high and can remain high even with treatment
