Medical Emergencies · patient case question
Patient D is in myxedema coma. Each of the following is a feature EXCEPT one. Which is the EXCEPTION?
Patient case: Five medication lists in one session
Patient: Four separate patients
Chief Complaint: A: denture soreness. B: needs an antibiotic before an extraction. C: routine review. D: brought in obtunded by her daughter.
Background: A, 68-year-old male: benign prostatic hyperplasia on terazosin, hyperlipidaemia on simvastatin. Denture stomatitis diagnosed today and systemic fluconazole considered. B, 90-year-old female: frail, on no regular medication. C, 71-year-old female: rheumatoid arthritis on methotrexate, osteoporosis on oral alendronate for six years. D, 79-year-old female: long-standing hypothyroidism, ran out of levothyroxine some weeks ago.
Vital Signs: D: T 94.6°F · HR 48 bpm · RR 8 · BP 96/58 mmHg · drowsy and confused
Findings: A: erythematous denture-bearing palatal mucosa. C: panoramic radiograph taken for pre-operative assessment.
Show answer and explanation
Correct answer: B. Tachycardia
- A. Hypoventilation with hypercapnia IS characteristic, caused by reduced central respiratory drive and respiratory muscle weakness. It is the usual mechanism of death and the reason airway support is a priority.
- B. CORRECT as the exception. Myxedema coma is the extreme end of HYPOthyroidism, so every system is slowed — the patient is BRADYCARDIC, as this one is at 48 bpm, with reduced cardiac output and hypotension. TACHYCARDIA belongs to the opposite emergency, THYROID STORM, alongside hyperthermia, agitation, tremor and atrial fibrillation. Confusing the two crises is exactly what this item tests.
- C. Hypothermia IS characteristic and is often profound, and it classically occurs WITHOUT shivering. A normal temperature in a hypothyroid patient who is also septic should be read as a warning sign rather than reassurance.
- D. Hyponatraemia IS characteristic, resulting from impaired free water excretion. Hypoglycaemia commonly accompanies it.
Note: Precipitants are cold exposure, infection, trauma, and — directly relevant to dentistry — SEDATIVES AND OPIOIDS. An undiagnosed or undertreated hypothyroid patient is exquisitely sensitive to CNS depressants, so sedation must be approached with real caution and elective care deferred until the patient is euthyroid. Treatment is intravenous levothyroxine with intravenous hydrocortisone and supportive care; mortality remains substantial even when treated.
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