What is metabolic alkalosis and what can it cause

Metabolic alkalosis occurs when the pH of the blood becomes more basic than it should, that is, when it is above 7.45, which arises in situations such as vomiting, use of diuretics or excessive consumption of bicarbonate, for example.

This is a serious change, as it can cause the imbalance of other blood electrolytes, such as calcium and potassium and cause symptoms such as weakness, headache, muscle changes, seizures or cardiac arrhythmia.

It is important that the body maintains its balanced pH, which should be between 7.35 and 7.45, for the body’s metabolism to function properly. Another worrying situation that can arise is when the pH is below 7.35, with metabolic acidosis. Find out what metabolic acidosis is and what causes it .

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What are the causes

Generally, metabolic alkalosis occurs due to the loss of the H + ion in the blood or the accumulation of sodium bicarbonate, which makes the body more basic. Some of the main situations that cause these changes are:

  • Excessive vomiting, a situation that causes loss of hydrochloric acid from the stomach;
  • Washing or aspiration of the stomach in the hospital;
  • Excessive consumption of drugs or alkaline foods, with sodium bicarbonate;
  • I use diuretic remedies, such as Furosemide or Hydrochlorothiazide;
  • Lack of potassium and magnesium in the blood;
  • Excessive use of laxatives;
  • A side effect of certain antibiotics, such as Penicillin or Carbenicillin, for example;
  • Kidney diseases, such as Bartter’s syndrome or Gitelman’s syndrome.

In addition to metabolic alkalosis, another reason for the blood pH to remain as a basic pH is respiratory alkalosis, caused by a lack of carbon dioxide (CO2) in the blood, causing it to become less acidic than normal, and it happens in situations like very fast and deep breathing. Find out more about what it is, causes and symptoms of respiratory alkalosis .

Main symptoms

Metabolic alkalosis does not always cause symptoms and, in most cases, it is the symptoms of the disease that cause alkalosis. However, symptoms such as muscle spasms, weakness, headache, mental confusion, dizziness, and seizures can also arise, mainly caused by changes in electrolytes such as potassium, calcium, and sodium.

What is the compensation?

Generally, when the blood pH changes, the body itself tries to correct this, as a way to avoid complications.

The compensation for metabolic alkalosis occurs mainly through the lungs, which start to have a slower breathing in order to retain more carbon dioxide (CO2) and increase the acidity of the blood. 

The kidneys also try to compensate by changing the absorption or excretion of substances in the urine, trying to eliminate more bicarbonate. However, other changes may appear together, in the blood or kidneys, such as dehydration or loss of potassium, for example, especially in severely ill people, which hinders the body’s ability to correct these changes.

How to confirm

The diagnosis of metabolic alkalosis is made through tests that measure blood pH, and it is also important to assess how the levels of bicarbonate, carbon dioxide and some electrolytes in the blood.

The doctor will also do the clinical evaluation to try to identify the cause. In addition, the dosage of chlorine and potassium in the urine may help to clarify the presence of renal changes in the electrolyte filtration.

How the treatment is done

To treat metabolic alkalosis, initially, it is necessary to treat its cause, be it gastroenteritis or use of certain medications, for example. In some cases, hydration through the vein with saline is necessary. 

Acetazolamide is a medicine that can be used to help eliminate bicarbonate from the urine in more worrying cases, however, in very severe cases, it may be necessary to administer acids directly into the vein or perform blood filtration through hemodialysis.

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