Myxoedema coma

Although very rare, severe hypothyroidism (especially in the elderly) may present with confusion or even coma.

Commonly presents with:

• Hypothermia
• Severe cardiac failure
• Hypoventilation
• Hypoglycaemia
• Hyponatraemia

Initial treatment (followed, eventually, by maintenance therapy):

• T₃ orally or IV in doses of 2.5-5μg every 8 hrs
• O₂ (by ventilator if necessary)
• Insertion of a Swan-Ganz catheter to monitor cardiac output/filling pressure
• Gradual re-warming
• Hydrocortisone 100mg IV 8-hourly
• Dextrose infusion (to prevent hypoglycaemia)

‘Myxoedema madness’:

Depression is common in hypothyroidism but occasionally (with severe hypothyroidism in the elderly) the patient may become frankly demented or psychotic, sometimes with striking delusions.

This may also occur shortly after starting T₄ replacement.