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Acid-Base Balance

Acid-Base Balance Overview

Your blood needs the right balance of acid and basic (alkaline) compounds to function properly. This is called the acid-base balance. Your kidneys and lungs work to keep the acid-base balance. Even slight variations from the normal range can have significant effects on your vital organs.

Acid and alkaline levels are measured on a pH scale. An increase in acidity causes pH levels to fall. An increase in alkaline causes pH levels to rise.

When the levels of acid in your blood are too high, it is called acidosis. When your blood is too alkaline, it is called alkalosis.

Respiratory acidosis and alkalosis are due to a problem with the lungs. Metabolic acidosis and alkalosis are due to a problem with the kidneys.

Each of these conditions is caused by an underlying disease or disorder. Treatment depends on the cause.

Respiratory Acidosis

When you breathe, your lungs remove excess carbon dioxide from your body. When they cannot do so, your blood and other fluids become too acidic.


Chest deformities or injuries can cause respiratory acidosis to develop. So can chronic diseases of the lungs or airways. Other causes include overuse of sedatives and obesity (if your lungs cannot fully inflate).     


In chronic respiratory acidosis, symptoms develop over time. Because it happens slowly, your kidneys may adjust and return your body to a normal acid-base balance. Acute respiratory acidosis comes on suddenly, leaving the kidneys no time to adjust.


Symptoms may include fatigue, shortness of breath, and confusion.


A complete physical examination is necessary. Diagnostic testing may include arterial blood gas test, metabolic panel, pulmonary function test, and chest X-ray.


Treatment is targeted to the cause. Bronchodilator medications can correct some forms of airway obstruction. If your blood oxygen level is too low, you may require oxygen. Noninvasive positive pressure ventilation (NPPV) or a breathing machine may be necessary.

If you smoke, you will be advised to stop.


Respiratory acidosis is serious and requires immediate medical attention. Potential complications include respiratory failure, organ failure, and shock.


You can take steps to help prevent some of the conditions that lead to respiratory acidosis. Maintain a healthy weight. Take sedatives only under strict doctor supervision and never combine them with alcohol. Do not smoke.

Metabolic Acidosis

Metabolic acidosis occurs either when your body produces too much acid, or when your kidneys are unable to remove it properly.  


There are three main types of metabolic acidosis. Diabetic acidosis, or diabetic ketoacidosis, is a buildup of ketone bodies. This is usually due to uncontrolled type 1 diabetes. Hyperchloremic acidosis is when your body loses too much sodium bicarbonate, often after severe diarrhea.

Lactic acidosis is when too much lactic acid builds up. This can be due to:

  • prolonged exercise
  • lack of oxygen
  • certain medications, including salicylates
  • low blood sugar (hypoglycemia)
  • alcohol
  • seizures
  • liver failure
  • cancer

Other things that can trigger metabolic acidosis include kidney disease and severe dehydration. Poisoning from ingestion of excess aspirin, ethylene glycol, and methanol are other causes.


Symptoms can include rapid breathing, fatigue, and confusion.


Severe cases can lead to shock and can be life threatening.                        


Diagnostic testing may include serum electrolytes, urine pH, and arterial blood gases. Once acidosis is confirmed, other tests may be necessary to pinpoint the cause.


The underlying condition behind the acidosis must be treated. In some cases, sodium bicarbonate is prescribed to return the blood to a normal pH.


Alkalosis is when alkaline levels are too high due to decreased carbon dioxide or increased bicarbonate. There are five kinds of alkalosis.

Respiratory alkalosis is when your blood has low levels of carbon dioxide. This can be caused by a number of factors, including:

  • lack of oxygen
  • high altitude
  • fever
  • lung disease
  • liver disease
  • salicylate poisoning

When you have alkalosis, your body works to get your acid levels back to normal. That can leave carbon dioxide and bicarbonate levels at abnormal levels. This is called compensated alkalosis.

When your blood has too much bicarbonate, it is called metabolic alkalosis. This can happen from prolonged vomiting. Prolonged vomiting can also make you lose too much chloride. This is called hypochloremic alkalosis. Some diuretic medicines can cause you to lose too much potassium. This is called hypokalemic alkalosis.


Symptoms of alkalosis may include:

  • muscle twitching, hand tremor, muscle spasms
  • numbness and tingling
  • nausea, vomiting
  • lightheadedness, confusion


In severe cases, alkalosis can lead to arrhythmias or coma.


Along with a physical exam, diagnostic testing for alkalosis may include a metabolic panel, blood gas analysis, urinalysis, and urine pH.


Some medications can help correct chemical losses. Further treatment will depend on the cause.

Content licensed from:

Written by: Ann Pietrangeloon: Nov 02, 2016

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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