What is the Trousseau sign and what does it indicate?

• A. Carpal spasm with cuff inflation; hyperkalemia
• B. Facial grimace with tapping; hypokalemia
• C. Hand tremor with finger extension; hypercalcemia
• D. Carpal spasm with cuff inflation; hypocalcemia

Answer: (D)

The Trousseau sign is a test for latent tetany due to low calcium. When a blood pressure cuff is inflated above the systolic pressure for several minutes, it cuts off blood flow and induces forearm ischemia. In someone with hypocalcemia, the nerves and muscles become highly excitable, and the ischemia triggers a carpal spasm: the wrist and metacarpophalangeal joints flex, the interphalangeal joints extend, and the fingers clamp in a characteristic hand posture with the thumb often adducted. This is a positive sign and points to hypocalcemia as the underlying issue (hypoparathyroidism, severe vitamin D deficiency, chronic kidney disease, pancreatitis, etc.). It’s distinct from Chvostek sign, which is a twitch in facial muscles on tapping the facial nerve, and it’s not seen with hypercalcemia, where neuromuscular excitability is reduced.