CO2

Definition

Serum CO2 is a blood test that measures the amount of carbon dioxide (CO2) in serum (the liquid portion of the blood).

Serum CO2 is really a measure of serum HCO3-, also called bicarbonate. The procedure used to measure HCO3- in the laboratory first converts it to CO2. In the body, 95% of the CO2 is present as HCO3-, so most of what is measured in the laboratory represents HCO3-.

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children: The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding.

CO2 and bicarbonate are also measured as part of an arterial blood gas analysis.

How to prepare for the test

The health care provider may advise you to discontinue drugs that may affect the test.

How the test will feel

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

The CO2 levels in the blood are influenced by kidney and respiratory (lung) function.

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

What the risks are

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

Special considerations

Drugs that can increase HCO3- measurements include corticosteroids and excessive use of antacids.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Page Content:

Bicarbonate test; HCO3-; Carbon dioxide ; hco3; hco3 name; carbon dioxide; analyzer carbon dioxide; carbon cycle dioxide oxygen; carbon dioxide poisoning; carbon cycle dioxide; carbon dioxide emissions; carbon dioxide effects; carbon dioxide gas; carbon dioxide global warming; analyzer carbon dioxide gas; atmospheric carbon dioxide; carbon dioxide laser; carbon detector dioxide; carbon dioxide level; carbon dioxide plant; carbon dioxide use; blood carbon dioxide in; carbon dioxide effect global green house warming; carbon dioxide source; carbon dioxide liquid; carbon density dioxide; carbon dioxide sink; atmosphere carbon dioxide in; carbon dioxide emission; carbon dioxide properties; carbon dioxide msds; carbon dioxide make; carbon dioxide sensor; carbon dioxide test; carbon dioxide sequestration; carbon dioxide testing; carbon dioxide poisoning symptom; carbon dioxide molecule; carbon dioxide effect green house; blood carbon dioxide in low; carbon cycle dioxide worksheet; call carbon dioxide it life we; car carbon dioxide; carbon cleaning dioxide; carbon dioxide removal; carbon dioxide scrubber; carbon dioxide tank; activity carbon dioxide emission from human; blood carbon dioxide test; carbon dioxide transport; carbon dioxide production; carbon dioxide retention; carbon dioxide monitor; carbon definition dioxide; carbon dioxide generator; carbon diagram dioxide phase; carbon dioxide equipment hire; carbon dioxide oxygen; carbon dioxide low; carbon come dioxide does from where; carbon dioxide formula; carbon cylinder dioxide; carbon define dioxide; carbon dioxide supercritical; carbon dioxide pollution; blood carbon dioxide in level; carbon commercial dioxide; carbon dioxide mosquito trap; blood carbon dioxide level; breathe carbon dioxide human; carbon dioxide extinguisher fire; carbon dioxide price; carbon dioxide fixation; carbon dioxide meat red through; carbon dioxide mosquito; carbon dioxide narcosis; carbon dioxide picture; carbon dioxide storage; absorbent carbon dioxide; acidosis carbon dioxide; carbon dioxide water; bloodstream carbon dioxide in; carbon dioxide handling safety; carbon dioxide in solubility water; carbon dioxide high level; carbon dioxide liquid supercritical; buildup carbon dioxide; carbon dioxide epco; carbon dioxide fact; carbon dioxide information; carbon dioxide partial pressure; carbon dioxide tree; body carbon dioxide in; carbon dioxide in soda; carbon dioxide supplier; blood carbon dioxide; carbon chemical dioxide formula; carbon dioxide pathway; carbon dioxide photosynthesis; carbon dioxide safety video; blood carbon dioxide in level low; carbon dioxide experiment; carbon dioxide resources,pdf; carbon dioxide volcano; calcium carbon dioxide inorganic oxide reaction solvent