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