Trousseau Sign · What Is It, Causes, and More

Trousseau’s sign is a classic indicator of low calcium levels in the blood (i.e., hypocalcemia). Hypocalcemia can result from a wide variety of conditions, but it is most commonly seen in individuals with low levels of parathyroid hormone (i.e., hypoparathyroidism) or vitamin D deficiency. Less often, hypocalcemia can occur when too much calcium leaves the blood, which can happen due to kidney failure, acute pancreatitis, severe infections, or treatment with several medications. Finally, other metabolic abnormalities (e.g., magnesium deficiency) or disorders of the acid-base balance (e.g., metabolic alkalosis) can be contributing factors to hypocalcemia.

Trousseau’s sign can be checked while monitoring one’s vital signs (e.g., heart rate, blood pressure, respiratory rate, etc.). It can be triggered by placing a blood pressure cuff, or sphygmomanometer cuff, on an individual’s arm and inflating it to a pressure greater than their systolic blood pressure for 2 to 3 minutes. The cuff will block the brachial artery (i.e., the main blood vessel of the arm), and if the individual has hypocalcemia, their arm muscles will activate involuntarily, making the wrist and parts of the hand move. A positive Trousseau’s sign is defined by flexion of the wrist, the thumb, and the joints located between the palm of the hand and the fingers (i.e., metacarpophalangeal joints), along with the extension of the fingers. 

The Trousseau sign of latent tetany is a way to determine if an individual may have hypocalcemia. Trousseau’s sign is considered positive when a carpopedal spasm of the hand and wrist occurs after an individual wears a blood pressure cuff inflated over their systolic blood pressure for 2 to 3 minutes.