The nurse taking the blood pressure of a patient who had a total thyroidectomy 2 days earlier notes that the patient's hand goes into a carpopedal spasm; this movement is an indication of:

• A. Hyperkalemia, called the Allen sign
• B. Hypernatremia, called the Hogan sign
• C. Hypocalcemia, called the Trousseau sign
• D. Hypokalemia, called the Chvostek sign

Answer: (C)

This is hypocalcemia causing neuromuscular irritability, manifested as tetany. After thyroidectomy, the parathyroid glands may be damaged or removed, leading to decreased parathyroid hormone and low calcium levels. When a blood pressure cuff is inflated above the systolic pressure for several minutes, the resulting ischemia lowers ionized calcium at the nerves and muscles, producing a carpopedal spasm—the Trousseau sign. This sign is specifically associated with hypocalcemia and is a classic clinical indicator of acute or latent tetany. Chvostek sign, the facial twitch elicited by tapping the facial nerve, can also occur with hypocalcemia but is not the mechanism shown here. Hyperkalemia or hypernatremia do not produce this cuff-induced hand spasm, and signs like Allen or Hogan are not relevant to this electrolyte disturbance.