Introduction

Tetany is a condition whereby a person experiences uncontrollable muscle movements. It happens when there is an abnormality in the levels of some chemicals in the bloodstream, especially if a person has a low level of calcium. Low levels of calcium in the blood is referred to as hypocalcemia.¹ The telltale symptoms of tetany include feeling numb around the mouth, muscle cramps and various sensations in the hands and feet. In severe cases, tetany can cause seizures and spasms of the voice box (larynx).^1,2 Spasms of the voice box are referred to as laryngospasms and may cause disturbances in speech and breathing. The symptoms of tetany range to being severe such that they may be life threatening.

Alkalosis is one of the causes of tetany. Alkalosis comes about when the pH of the blood rises to become alkaline. This article will detail the relationship between tetany and alkalosis, and how these conditions may be resolved when they co-occur.

Overview of tetany

Tetany is a condition whereby a person experiences involuntary muscle cramping, twitching and spasms. It happens when a person has abnormal levels of certain nutrients or an imbalance of other factors. As a result of low levels of electrolytes, the peripheral nervous system becomes activated to result in the symptoms that are observed in tetany.³ The most common symptom of tetany is paraesthesia, whereby a person may have a feeling of pins and needles accompanied by burning or numbness. Paraesthesia is commonly felt in the limbs, hands and feet.¹ Tetany may also cause nausea and vomiting. 

Listed below are some of the specific causes of tetany. Worth mentioning is that these causes of tetany are also interlinked.³

• Hypocalcemia: This is when there are very low levels of calcium in the blood. The most common cause of hypocalcemia is a low level of the parathyroid hormone in blood. The parathyroid hormone is important for the uptake of calcium from food in the intestines
• Hypomagnesemia: This is when there are very low levels of magnesium in the bloodstream. There are various causes of hypomagnesemia. These include various diseases, alcohol abuse and certain medications
• Hypokalemia: This is when there are very low levels of potassium in the blood. Hypokalemia can be caused by an excessive loss of potassium through vomiting or diarrhoea 
• Alkalosis: This is a metabolic state whereby the pH of the blood rises above normal levels. Alkalosis is caused by various factors that have to do with the balance of nutrients in the bloodstream. This includes the nutrients that are mentioned above

Overview of alkalosis

Alkalosis is the state of having a blood pH that is alkaline as a result of numerous factors, including some diseases. Alkalosis may other be metabolic or respiratory. Metabolic alkalosis is usually caused by low levels of calcium or potassium in the bloodstream, as well as an increase in the levels of bicarbonate. Respiratory alkalosis on the other hand is caused by not breathing properly, leading to a decrease of carbon in the bloodstream. Respiratory alkalosis is caused by hyperventilation due to a number of reasons. These reasons include respiratory diseases such as asthma and chronic obstructive pulmonary disorder (COPD). Heart attacks, pregnancy and panic attacks may also be a cause of hyperventilation.^4,5

How alkalosis contributes to tetany

Alkalosis is believed to be a contributing factor when it comes to tetany. One way in which alkalosis may cause tetany is by causing a disturbance in the levels of electrolytes, and it causes a decrease in the free calcium ions of the bloodstream⁶. This is because an increase in the blood pH makes more calcium ions to bind to the proteins that are found in the bloodstream, particularly albumin. Hyperventilation leads to respiratory alkalosis as there is an excessive release of carbon dioxide which causes blood pH to rise.⁴ Individuals that are likely to hyperventilate may experience tetany that is induced by alkalosis.⁵ Panic attacks are a leading cause of hyperventilation. Alkalosis is also linked to hypokalemia, which is referred to as hypokalemic metabolic alkalosis. Metabolic alkalosis may cause hypokalemia, whereas hypokalemia may also cause alkalosis. Metabolic alkalosis may be caused by excessive vomiting, especially through vomiting which causes a loss of stomach acid. The use of medications referred to as diuretics also causes alkalosis. Diuretics are medications that cause excessive urination.

Preventative measures

As alkalosis is one of the leading causes of tetany, preventative measures should also be applied to prevent it. To prevent respiratory alkalosis, individuals that suffer from conditions that cause hyperventilation should take measures to control those conditions. Hyperventilation may be caused by conditions such as anxiety, asthma and COPD. People with anxiety should keep their stress levels low in order to avoid attacks which cause hyperventilation. For respiratory diseases, medications that are used to control these conditions should be taken in order to prevent breathlessness and hyperventilation.

For metabolic alkalosis, hypokalemia should be avoided by ensuring proper hydration. The use of diuretic medication should also be taken into consideration as diuretics could lead to excessive loss of potassium. Repeated vomiting should also be monitored as it could lead to an imbalance of nutrients.

FAQs

What is alkalosis?

Alkalosis is a condition whereby the pH of the blood rises above 7.45 and becomes alkaline.

How is tetany caused by alkalosis?

Alkalosis causes an imbalance in some of the nutrients in the bloodstream, including calcium and potassium. This then leads to tetany.

What is the link between alkalosis and calcium?

When the levels of calcium in the bloodstream are too low, muscle spasms may occur due to the peripheral nervous system being activated.

How are muscles affected by tetany?

Due to the peripheral nervous system being over excited, it causes the muscles to spasm or even cramp.

How can hyperventilation lead to tetany?

When a person breathes rapidly or deeply, the body loses more carbon dioxide than it should. As a result, the pH of the blood rises to cause a lack of free calcium. This may then lead to tetany.

What is the link between respiratory acidosis and hypocalcemia?

Respiratory acidosis comes about when the levels of carbon dioxide decrease due to hyperventilation. As a result of respiratory acidosis, the levels of calcium in the bloodstream drop sharply.

Summary

Alkalosis is a state whereby the body experiences a rise in pH due to a number of factors. As a result of the rise in pH, nutritional imbalances can take place, leading to tetany. Tetany is a condition whereby a person experiences muscle spasms, twitching and cramps. In some cases, tetany can even cause spasms of the larynx, nausea and vomiting.

Alkalosis is either respiratory or metabolic. With respiratory alkalosis, a person that is hyperventilating may lose too much carbon dioxide, leading to a rise in the pH of their bloodstream. This rise in pH causes a sharp drop in the levels of available calcium. Low levels of calcium can then lead to the involuntary muscle movements that are seen in tetany. On the other hand, metabolic alkalosis is linked to an excessive loss of fluids and has to do with a drop of potassium levels. This can also trigger tetany. There are various ways in which alkalosis-induced tetany can be prevented. For people that tend to or find themselves hyperventilating, they need to address the underlying causes. People with anxiety may tend to hyperventilate during panic attacks. So in such cases, stress should be managed. With metabolic alkalosis, repeated vomiting and fluid loss could lead to a rise in blood pH.