Tetany

Overview

Tetany is a condition in which the muscles contract involuntarily, producing cramps, spasms, and twitching, most often in the hands, feet, and face. It happens when the nerves and muscles become overly excitable. This overexcitability is usually due to an imbalance of minerals in the blood, most commonly a low level of calcium.

Tetany is a sign that something has disturbed the body's mineral balance or acid level, so it is important to find and treat the underlying cause. Mild tetany may cause tingling and minor cramps, but severe tetany can affect the muscles used for breathing and may be dangerous, making prompt medical evaluation important. Because tetany is a sign rather than a diagnosis in itself, treatment depends on correcting whatever imbalance or condition is causing the nerves and muscles to misfire.

Symptoms

Symptoms reflect overactive nerves and muscles and can range from mild to severe.

• Tingling or a pins-and-needles sensation around the mouth, fingers, and toes
• Muscle cramps and twitching
• Painful spasms of the hands and feet, sometimes with the hands drawing into a characteristic position
• Muscle stiffness
• In severe cases, spasms of the voice box or chest muscles causing breathing difficulty, and seizures

Severe spasms, trouble breathing, or a seizure are medical emergencies and require immediate care. Even milder, recurring symptoms should be evaluated to find the cause.

Causes

Tetany results from overexcitable nerves and muscles, usually due to a mineral or acid-base imbalance.

• Low calcium (hypocalcemia): The most common cause, which can result from underactive parathyroid glands, vitamin D deficiency, kidney disease, or other conditions.
• Low magnesium: Magnesium deficiency can lower calcium and trigger tetany.
• Acid-base disturbances: Overbreathing (hyperventilation) can change blood chemistry and bring on tetany even when total calcium is normal.
• Other imbalances: Certain potassium and other electrolyte problems.

Identifying which imbalance is responsible guides treatment, because correcting the specific problem, whether it is calcium, magnesium, or an acid-base disturbance, is what relieves the spasms and prevents them from coming back.

Risk Factors

• Underactive parathyroid glands (hypoparathyroidism), including after neck or thyroid surgery
• Vitamin D deficiency
• Kidney disease
• Magnesium deficiency, sometimes from poor nutrition, alcohol use, or certain medications
• Conditions that cause hyperventilation, such as severe anxiety or panic

Diagnosis

Diagnosis focuses on confirming tetany and finding the underlying imbalance.

• Blood tests: Measuring calcium, magnesium, potassium, phosphate, vitamin D, parathyroid hormone, and kidney function.
• Physical signs: Doctors may check for signs of nerve overexcitability, such as facial twitching when a nerve is tapped or hand spasm when blood flow is briefly restricted.
• Other tests: Depending on the suspected cause, such as kidney or hormone evaluation, or blood gas testing if overbreathing is suspected.

Treatment

Treatment aims to relieve the spasms and correct the underlying imbalance.

• Correcting low calcium: Calcium given by vein for severe or acute tetany, and calcium with vitamin D by mouth for ongoing low levels.
• Correcting magnesium: Magnesium replacement when it is low, since this often must be fixed for calcium to normalize.
• Treating the cause: Managing parathyroid problems, kidney disease, or vitamin D deficiency.
• For hyperventilation: Calming and slowing the breathing, and addressing the underlying anxiety or trigger.

Severe tetany with breathing difficulty or seizures is treated urgently in a medical setting, where the mineral levels can be corrected quickly and monitored closely until the person is stable.

Prevention

• Treat and monitor conditions that affect calcium, such as parathyroid disorders and kidney disease
• Maintain adequate vitamin D and a balanced diet with enough calcium and magnesium
• Take prescribed calcium and vitamin D supplements as directed if you are at risk
• Manage anxiety and panic to reduce hyperventilation-related episodes
• Keep regular follow-up after thyroid or parathyroid surgery

When to See a Doctor

See a doctor if you have recurring muscle cramps, spasms, or tingling around the mouth, fingers, and toes, so that blood tests can check for a mineral imbalance and identify the cause.

Call emergency services immediately for severe spasms, difficulty breathing, spasm of the throat or voice box, chest tightness, or a seizure. These can be life-threatening and need urgent treatment to correct the underlying imbalance.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Tetany.
2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Hypoparathyroidism.
3. Mayo Clinic. Hypocalcemia and hypoparathyroidism.
4. National Institutes of Health (NIH), Office of Dietary Supplements. Calcium and Magnesium.