Trousseau's sign

A carpopedal spasm induced by brachial artery occlusion with a blood pressure cuff inflated above systolic pressure for several minutes, indicating latent tetany and increased neuromuscular excitability. Possible causes are hypocalcemia, hypomagnesemia, hypoparathyroidism, vitamin D deficiency, chronic kidney disease, hypokalemia, alkalosis, and citrate toxicity from massive blood transfusion.