What Is It, Causes, and More
Author: Anna Hernández, MD
Editors: Ahaana Singh, Józia McGowan, DO, FACOI, FNAOME, CS
Illustrator: Abbey Richard
Copyeditor: Joy Mapes
What is the Trousseau sign?
The Trousseau sign of latent tetany is one of the clinical signs associated with hypocalcemia, or low calcium levels in the blood. This sign was originally described in 1861 by French physician Armand Trousseau. Trousseau’s sign refers to the involuntary contraction of the muscles in the hand and wrist (i.e., carpopedal spasm) that occurs after the compression of the upper arm with a blood pressure cuff.
The Trousseau sign of latent tetany should be distinguished from the Trousseau sign of malignancy, otherwise known as Trousseau syndrome, or migrating thrombophlebitis. The Trousseau sign of malignancy occurs when blood clots appear unexpectedly in superficial veins, and then, over time, migrate to different locations.
What causes Trousseau’s sign?
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.Hypocalcemia can affect a number of cellular processes, including neuron activity. Normally, calcium ions stabilize the resting potential of neurons. With hypocalcemia, neurons are less stable and more likely to fire spontaneously, which can trigger tetany, or the involuntary contraction of muscles. This increased neuromuscular excitability is what causes Trousseau’s sign, as well as other clinical manifestations, such as Chvostek sign, which is when facial muscles twitch after the facial nerve is tapped lightly on the upper cheek, just in front of the ear.
How do you check Trousseau’s sign?
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.
What are the most important facts to know about the Trousseau sign?
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.
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Resources for research and reference
Hall, J. (2015). Guyton and Hall textbook of medical physiology (13th ed.). Philadelphia, PA: Elsevier.
Jesus, J., & Landry, A. (2012). Images in clinical medicine. Chvostek's and Trousseau's signs. The New England Journal of Medicine, 367(11): e15. DOI:10.1056/NEJMicm1110569Patel, M., & Hu, E. (2020, July 18). Trousseau sign. In StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK557832/