Which feature best characterizes a myxedema crisis?

• A. Bradycardia with delayed relaxation of deep tendon reflexes
• B. Tachycardia with hyperreflexia
• C. Hyperthermia and tachycardia
• D. Hypertension and warm skin

Answer: (A)

In a myxedema crisis, severe hypothyroidism drives the body's systems to slow dramatically. This results in bradycardia because reduced metabolic demand lowers cardiac output and sympathetic drive. It also causes neuromuscular slowing, so deep tendon reflexes take longer to relax after a stimulus—a classic finding in hypothyroid states often described as a “hung-up” reflex. That combination—slow heart rate and delayed relaxation of reflexes—best captures the hallmark of a myxedema crisis.

Choices describing tachycardia with hyperreflexia, hyperthermia with tachycardia, or hypertension with warm skin point more toward thyrotoxic states (thyroid storm) or other hypermetabolic processes, not severe hypothyroidism.