What is Tetany?

What is Tetany?
on Mon 28 Nov


“Tetany” is the name given to an involuntary cramping, spasms or contractions in your muscles.


This usually occurs as a mild cramping in your hands and feet or your arms and legs. However, more seriously, this overly stimulated neuromuscular activity can extend into your larynx which then causes breathing problems.


It can also cause convulsions or seizures, significant muscle pain and heart dysfunction.


Causes of Tetany

Tetany is caused by an imbalance of your body’s electrolytes. This can be too little magnesium or potassium but is most often triggered by low levels of calcium which is known as “hypocalcaemia”


The cramping or spasms come about because the activity threshold for the activation of neurons is lowered by the lack of calcium in the body,  which then causes them to fire spontaneously and trigger the involuntary action of the muscles. The symptoms tend to reflect the severity and rapidity of onset of the hypocalcaemia.


Hypocalcaemia can be caused  by septic shock, kidney failure, significant blood loss, pancreatitis, severe vitamin D deficiency, magnesium deficiency and, rarely,  in cancers that involve bone.


It’s most often caused by low levels of parathyroid hormone whose job it is to control calcium levels. This condition is known as “hypoparathyroidism” and is a recognised complication of thyroid surgery.


It can temporarily be in up to 20% of patients after a thyroidectomy and be permanent in up to 5% depending on the complexity of surgery. Rarely, it can occur spontaneously due to autoimmune destruction of the parathyroid glands.



Tetany is a symptom rather than a disease and, since it can affect many different parts of the body, diagnosis is often difficult.


However, Tetany which is  caused by low calcium levels is often spotted through the (usually) subtle spasm of the wrist and thumb which occurs when a blood pressure cuff is used on the arm.  This is called the “Trousseau’s sign.”


Another indication is something called the “Chvostek’s sign” which is when facial muscles twitch when an individual’s cheek is tapped just in front of the ear,



The goal of treatment is to correct any electrolyte imbalance , but as tetany is triggered by differing conditions it is vital to treat the triggers themselves if possible.


When this is triggered acutely by low calcium levels,  it is a medical emergency and the most common approach is to inject calcium directly into the bloodstream.


However, where there is an ongoing risk such as hypoparathyroidism, the treatment will depend on the cause. Patients with chronic hypoparathyroidism will need to take daily doses of calcium and activated forms of Vitamin D for improved absorption on an ongoing basis.


If you are experiencing unexplained cramping as described in this blog post my recommendation is that you visit your GP. I hope this has been helpful.


Although every effort is made to ensure that all health advice on this website is accurate and up to date it is for information purposes and should not replace a visit to your doctor or health care professional.


As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link


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