Myxedema Coma
A severe, life-threatening exacerbation of hypothyroidism is called myxedema coma. 1, 2
Clinical Definition and Characteristics
Myxedema coma represents the most extreme manifestation of hypothyroidism and constitutes a medical emergency. 1, 2 This condition is characterized by:
- Poor circulation and hypometabolism 2
- Hypothermia 3
- Hypotension 3
- Altered mental status 3
- Mortality rate up to 30% even with intensive care treatment 3
The FDA drug label for levothyroxine explicitly warns that myxedema coma is a life-threatening emergency that results in unpredictable absorption of oral thyroid hormone from the gastrointestinal tract. 2
Critical Management Considerations
Oral thyroid hormone products are NOT recommended for treating myxedema coma. 2 Instead:
- Intravenous thyroid hormone formulations must be administered 2
- Treatment requires intensive care unit management 3
- The gastrointestinal hypometabolism prevents reliable absorption of oral levothyroxine 2
Clinical Context
While the American College of Obstetricians and Gynecologists notes that myxedema coma is rare, affecting only a small percentage of pregnant women with hyperthyroidism (in the context of thyroid storm, the hyperthyroid equivalent), 1 the condition represents the end-stage of untreated or severely undertreated hypothyroidism. 3
Myxedema (non-pitting edema) itself is a symptom of hypothyroidism, 4 but myxedema coma represents the decompensated state with systemic failure. Untreated hypothyroidism can progress through stages of increasing severity, ultimately leading to this life-threatening complication. 3, 5
Prevention Through Adequate Treatment
The risk of progression to myxedema coma underscores the importance of: