What is a life-threatening complication of poorly treated hypothyroidism?

• A. Goiter
• B. Myxedema coma
• C. Thyrotoxic storm
• D. Hyperparathyroidism

Answer: (B)

A key idea here is that myxedema coma represents the most severe, life-threatening progression of untreated hypothyroidism. When thyroid hormone is chronically deficient, the body's metabolic processes slow to a crawl. If decompensation occurs, mental status can deteriorate to stupor or coma, breathing can become shallow, the temperature can drop, and blood pressure and heart rate can fall. The result is multisystem failure with risks of severe hyponatremia, hypoglycemia, and respiratory depression. This is what makes myxedema coma an emergency that requires intensive care, including IV thyroid hormone replacement, aggressive supportive care, temperature management, fluid and electrolyte correction, glucose monitoring, and often glucocorticoids until adrenal insufficiency is ruled out.

Goiter is simply an enlarged thyroid and not by itself a life-threatening emergency, though it can cause symptoms if large. A thyrotoxic storm is the dangerous crisis of excess thyroid hormone seen in hyperthyroidism, not hypothyroidism. Hyperparathyroidism involves the parathyroid glands and calcium balance, and is not the acute life-threatening complication of untreated hypothyroidism.