Makindo Medical Notes

🧊 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

• Myxoedema and Coma (Severe Hypothyroidism) – NCBI Bookshelf
• Myxoedema Coma: Diagnosis and Treatment – AAFP