Myxoedema coma
🧊 Myxoedema coma is a rare but life-threatening complication of severe hypothyroidism.
Most patients have neither classical non-pitting oedema (myxoedema) nor coma.
⚠️ The key clinical clue is deterioration of mental status, often mistaken for delirium in elderly patients — particularly in women during winter months.
📖 About
- Extremely rare but carries high mortality.
- First described in London in 1879 by Ord.
- Represents end-stage untreated or decompensated hypothyroidism.
👵 Risk Groups
- Age >65 years, especially elderly women (4× more common).
- Undiagnosed or poorly controlled hypothyroidism.
- Patients non-compliant with thyroxine therapy.
⛔ Precipitating Factors
- Infections (pneumonia, UTI, sepsis).
- Cardiac disease: heart failure, MI, arrhythmias.
- CNS insults: stroke, subdural haematoma.
- Medications: sedatives, opioids, benzodiazepines, amiodarone, lithium.
- Hypothermia, trauma, surgery.
🩺 Clinical Features
- Goitre or post-thyroidectomy scar may be present.
- Skin: cool, dry, doughy; alopecia; coarse sparse hair.
- Facial swelling, periorbital oedema, macroglossia, ptosis.
- Neurology: hypoactive delirium, confusion, coma, seizures.
- Gastrointestinal: paralytic ileus, constipation, “myxoedema megacolon.”
- Cardiorespiratory: bradycardia, hypotension, hypoventilation, pericardial effusion, heart failure.
- Temperature: profound hypothermia (as low as 23°C).
🧪 Investigations
- FBC: normocytic or macrocytic anaemia, raised WCC if infection.
- U&Es: hyponatraemia, AKI.
- LFTs: elevated AST/ALT.
- TFTs: high TSH + low T4 (or low TSH in secondary disease).
- Blood glucose: hypoglycaemia.
- CK and troponin: may be raised.
- CXR: pneumonia, pleural effusion, cardiomegaly.
- ECG: bradycardia, low voltage, prolonged QT.
- Echocardiogram: pericardial effusion, tamponade risk.
- Blood cultures: look for sepsis.
- CT head: exclude stroke or intracranial bleed.
💊 Treatment Controversy:
Whether to use LT4 alone or LT4 + LT3 is debated.
⚠️ Higher mortality reported with large initial doses (>500 mcg T4 or >75 mcg T3/day).
Expert endocrine input is essential.
🚑 Management (Specialist / ITU Care)
- ABCDE approach: oxygen, IV access, cardiac monitoring, treat precipitant.
- Hydrocortisone 100 mg IV 6-hourly (cover for adrenal insufficiency).
- Thyroid hormone replacement:
- LT3 (liothyronine) 10–20 mcg IV every 12h, given slowly.
- LT4 25–50 mcg PO/NG/IV daily (slower onset but safer in cardiac disease).
- Once stable, convert to regular LT4 (50 mcg PO daily, titrate upwards).
- Supportive:
- Hypoglycaemia → IV glucose.
- Sepsis → IV antibiotics (e.g. Co-amoxiclav 1.2 g IV TDS).
- Hypothermia → blankets, avoid active rewarming.
- Hypoventilation → early intubation and ventilation if needed.
- Hyponatraemia → fluid restriction (unless severe/symptomatic).
- Hypotension → cautious fluids; inotropes if refractory.
📉 Prognosis
- Mortality remains high despite treatment.
- Deaths usually due to sepsis, GI bleed, or respiratory failure.
- Poor prognostic markers: advanced age, persistent hypothermia, altered consciousness.
📚 References
