CO2

Alternative names:

bicarbonate test; HCO3-

Normal values:

The normal range is 20-29 mEq/L.

Note: mEq/L = milliequivalent per liter

What abnormal results mean:

Lower-than-normal levels of HCO3- may indicate:

• ketoacidosis
• lactic acidosis
• kidney disease
• diarrhea
• methanol poisoning
• ethylene glycol poisoning
• Addison's disease (adrenal gland insufficiency)

Greater-than-normal levels of HCO3- may indicate:

• excessive vomiting
• respiratory dysfunction (breathing disorders)
• hyperaldosteronism
• Cushing's syndrome

Note: The kidneys are the organ primarily responsible for maintaining the normal levels of HCO3-. Metabolic acidosis (pH < 7.35 and HCO3- < 20 mEq/L) is a symptom of renal disease. However, HCO3- levels are also decreased in the presence of organic acids, (ketone bodies in diabetic ketoacidosis) because HCO3- is used to neutralize the acids.

Additional conditions under which the test may be performed:

• alkalosis
• delirium
• dementia
• renal tubular acidosis; distal
• renal tubular acidosis; proximal