Acidosis is a condition in which there is too much acid in the body fluids. It is the opposite of alkalosis (a condition in which there is too much base in the body fluids).
The kidneys and lungs maintain the balance (proper pH level) of chemicals called acids and bases in the body. Acidosis occurs when acid builds up or when bicarbonate (a base) is lost. Acidosis is classified as either respiratory or metabolic acidosis.
Respiratory acidosis develops when there is too much carbon dioxide (an acid) in the body. This type of acidosis is usually caused when the body is unable to remove enough carbon dioxide through breathing. Other names for respiratory acidosis are hypercapnic acidosis and carbon dioxide acidosis. Causes of respiratory acidosis include:
- Chest deformities, such as kyphosis
- Chest injuries
- Chest muscle weakness
- Long-term (chronic) lung disease
- Neuromuscular disorders, such as myasthenia gravis, muscular dystrophy
- Overuse of sedative drugs, causing decreased respiration
Metabolic acidosis develops when too much acid is produced in the body. It can also occur when the kidneys cannot remove enough acid from the body. There are several types of metabolic acidosis:
- Diabetic acidosis (also called diabetic ketoacidosis and DKA) develops when substances called ketone bodies (which are acidic) build up during uncontrolled diabetes.
- Hyperchloremic acidosis is caused by the loss of too much sodium bicarbonate from the body, which can happen with severe diarrhea.
- Kidney disease (uremia, distal renal tubular acidosis or proximal renal tubular acidosis).
- Lactic acidosis.
- Poisoning by aspirin, ethylene glycol (found in antifreeze), or methanol.
- Severe dehydration.
Lactic acidosis is a buildup of lactic acid. Lactic acid is mainly produced in muscle cells and red blood cells. It forms when the body breaks down carbohydrates to use for energy when oxygen levels are low. This can be caused by:
- Carbon monoxide poisoning
- Drinking too much alcohol
- Exercising vigorously for a very long time
- Liver failure
- Low blood sugar (hypoglycemia)
- Medicines, such as salicylates, metformin, anti-retrovirals
- MELAS (a very rare genetic mitochondrial disorder that affects energy production)
- Prolonged lack of oxygen from shock, heart failure, or severe anemia
- Sepsis -- severe illness due to infection with bacteria or other germs
- Severe asthma
Compensated acidosis occurs when the body returns the acid-base balance to near normal in cases of acidosis, but bicarbonate and carbon dioxide levels remain abnormal.
Metabolic acidosis symptoms depend on the underlying disease or condition. Metabolic acidosis itself causes rapid and deep breathing as your body tries to compensate for it. Confusion or lethargy may also occur. Severe metabolic acidosis can lead to shock or death.
Respiratory acidosis symptoms can include:
- Shortness of breath
Exams and Tests
The health care provider will perform a physical examination and ask about your symptoms.
Laboratory tests that may be ordered include:
- Arterial or venous blood gas analysis
- Basic metabolic panel (group of blood tests that measure sodium and potassium levels, kidney function, and other chemicals and functions) to show whether the type of acidosis is metabolic or respiratory
- Blood ketones
- Lactic acid test
- Urine ketones
- Urine pH
Other tests that may be needed to determine the cause of the acidosis include:
- Chest x-ray
- CT abdomen
- Urine pH
Treatment depends on the cause. Your provider will tell you more.
Acidosis can be dangerous if untreated. Many cases respond well to treatment.
Complications depend on the specific type of acidosis.
When to Contact a Medical Professional
All the types of acidosis will cause symptoms that require treatment by your provider.
Prevention depends on the cause of the acidosis. Many causes of metabolic acidosis can be prevented, including diabetic ketoacidosis and some causes of lactic acidosis. Normally, people with healthy kidneys and lungs do not have serious acidosis.
Oh MS, Briefel G, Pincus MR. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 15.
Sanghavi S, Albert TJ, Swenson ER. Acid-base balance. In: Broaddus VC, Ernst JD, King TE, et al. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 12.
Seifter JL. Acid-base disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 110.
Review Date 11/6/2021
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.