Metabolic acidosis

Metabolic acidosis is a disorder in which there is a high level of acid in the body fluids.

Metabolic acidosis is a pH imbalance of the blood in which the body has accumulated too much acid and does not have enough alkaline substances (such as bicarbonate) to balance the acids produced.

Blood pH measures the acidity of the blood. The blood has a normal pH range of 7.35 to 7.45. In metabolic acidosis, the pH is < 7.35.

The three main causes for metabolic acidosis are:

• Excessive acid production
• Diminished renal acid excretion
• Gastrointestinal or urinary loss of alkaline substances (bicarbonate)

Metabolic acidosis may be mild or severe. Severe metabolic acidosis is a serious disorder that may lead to shock or death.

The most common underlying causes of metabolic acidosis are:

• Diabetic ketoacidosis
• Intense exercise
• Prolonged fasting
• Drinking too much alcohol (alcoholism)
• Liver failure
• Cancer
• Drugs
• Severe dehydration
• Chronic kidney disease
• Severe anemia
• Seizures
• Prolonged lack of oxygen from shock
• Poisoning or overdose of methanol, ethylene glycol and salicylates (aspirin)

The symptoms of metabolic acidosis are usually due to the underlying disease.

In case of mild acidosis, it is usually asymptomatic. If there are symptoms, the most common ones are:

• Headache
• Lack of energy
• Sleepiness

If case of severe acidosis (pH < 7.1) the following symptoms may be present:

• Nausea and vomiting
• General malaise
• Lethargy and confusion
• Rapid and deep breathing (Kussmaul's breathing)
• Cardiac arrest with coma, shock or arrhythmias (severe acute acidosis)
• Inhibition of bone mineralization (chronic acidosis)

For the diagnosis of metabolic acidosis the following tests may be performed:

• Arterial blood gas test (blood pH <7.35)
• Urine pH test (urine pH may fall below 4.5)
• Blood test (hematology plus biochemistry with serum electrolyte measurement)
  • Potassium, glucose, ketones or lactic acid are above the normal ranges
  • Bicarbonate in the blood is low (usually less than 22 mEq/L)

The treatment consists mainly of identifying the underlying cause and treating it.

Sometimes, metabolic acidosis is treated by administering sodium bicarbonate (NaHCO3) and fluids intravenously (IV) to recover a proper acid-base balance.