Myxedema Coma Risk Factors
Myxedema coma is precipitated in patients with longstanding, often untreated or inadequately treated hypothyroidism when they are exposed to physiologic stressors including infection, sedatives/anesthetics, cold exposure, or other intercurrent illnesses. 1
Patient Demographics and Baseline Conditions
- Elderly women are at highest risk, particularly those over 60 years of age, with most cases occurring during winter months 2, 3
- Longstanding, severe hypothyroidism that is either undiagnosed or inadequately treated serves as the essential baseline condition 1, 4
- History of thyroid surgery (thyroidectomy) or radioactive iodine therapy with subsequent insufficient thyroxine replacement increases risk 4, 5
- Medication non-compliance or inadequate thyroid hormone replacement despite known hypothyroidism 5
Precipitating Factors (Critical Triggers)
Infections and Systemic Illness
- Pneumonia and other infections are among the most common precipitants and should be actively sought and treated 2, 3
- Any intercurrent illness that overwhelms the patient's compensatory mechanisms can trigger decompensation 2
Medications
- Sedatives and anesthetics are specifically identified as high-risk precipitants 1
- Surgery represents a major physiologic stressor that can precipitate myxedema coma 6
Environmental and Physiologic Stressors
Concurrent Endocrine Disorders
- Adrenal insufficiency (either primary or secondary) significantly increases risk, as rapid metabolic correction with thyroid hormone can precipitate acute adrenal crisis 1, 2
- Hypoglycemia must be identified and corrected immediately 7
Metabolic and Laboratory Risk Factors
- Hyponatremia is frequently present and should raise suspicion for hypothyroidism in any patient 2
- Hypoxemia and hypercarbia from respiratory depression 3
- Electrolyte disturbances beyond hyponatremia 1
Critical Pitfall to Avoid
Do not overlook hypothyroidism in patients presenting with hyponatremia, altered mental status, or unexplained coma—maintain a high index of suspicion as early recognition and treatment are essential to prevent mortality 2. The diagnosis must be considered in the differential of every comatose patient, as delayed treatment significantly worsens outcomes 4.