CO2

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Overview

Risks

Results

CO2

Alternative Names:

Bicarbonate test; HCO3-; Carbon dioxide

Normal Values:

The normal range is 20-29 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
Salicylate toxicity (such as aspirin overdose)
Ethylene glycol poisoning
Addison disease (adrenal gland insufficiency)

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

Excessive vomiting
Respiratory dysfunction (breathing disorders)
Hyperaldosteronism
Cushing syndrome

The kidneys are the organ primarily responsible for maintaining the normal levels of HCO3-. Metabolic acidosis (pH less than 7.35 and bicarbonate less than 20 meq/l) is a symptom of kidney 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
Any medical condition in which the examiner feels there might be a metabolic derangement

Review Date: 6/3/2005
Reviewed By: Thomas A. Owens, M.D., Departments of Internal Medicine and Pediatrics, Duke University Medical Center, Durham, NC. Review provided by VeriMed Healthcare Network.

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