BACK TOTOP Browse A-ZSearchBrowse A-ZABCDEFGHIJKLMNOPQRSTUVWXYZ0-9 E-mail FormEmail ResultsName:Email address:Recipients Name:Recipients address:Message: Print-FriendlyBookmarksbookmarks-menuCO2 blood testBicarbonate test; HCO3-; Carbon dioxide test; TCO2; Total CO2; CO2 test - serum; Acidosis - CO2; Alkalosis - CO2CO2 is carbon dioxide. This article discusses the laboratory test to measure the amount of carbon dioxide in the liquid part of your blood, called the serum.In the body, most of the CO2 is in the form of a substance called bicarbonate (HCO3-). Therefore, the CO2 blood test is really a measure of your blood bicarbonate level. How the Test is Performed A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.Blood is drawn from a veinVenipuncture is the collection of blood from a vein. It is most often done for laboratory testing.ImageRead Article Now Book Mark Article How to Prepare for the Test Many medicines can interfere with blood test results.Your health care provider will tell you if you need to stop taking any medicines before you have this test. DO NOT stop or change your medicines without talking to your provider first. How the Test will Feel You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn. Why the Test is Performed The CO2 test is most often done as part of an electrolyte or basic metabolic panel. Changes in your CO2 level may suggest that you are losing or retaining acidic fluid. This may cause an imbalance in your body's electrolytes.ElectrolyteElectrolytes are minerals in your blood and other body fluids that carry an electric charge. Electrolytes affect how your body functions in many ways...Read Article Now Book Mark Article CO2 levels in the blood are affected by kidney and lung function. The kidneys help maintain the normal bicarbonate levels. Normal Results The normal range is 23 to 29 milliequivalents per liter (mEq/L) or 23 to 29 millimoles per liter (mmol/L).Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.The example above shows the common measurement range of results for these tests. Some laboratories use different measurements or may test different specimens. What Abnormal Results Mean Abnormal levels may be due to the following problems:Lower-than-normal levels:Addison disease Addison diseaseAddison disease is a disorder that causes the adrenal glands to not produce enough hormones.ImageRead Article Now Book Mark Article Carbonic anhydrase inhibitors (used to treat glaucoma) Diarrhea DiarrheaDiarrhea is when you pass loose or watery stool.ImageRead Article Now Book Mark Article Ethylene glycol poisoning Ethylene glycol poisoningEthylene glycol is a colorless, odorless, sweet-tasting chemical. It is poisonous if swallowed. Ethylene glycol may be swallowed accidentally, or it...ImageRead Article Now Book Mark Article Ketoacidosis KetoacidosisDiabetic ketoacidosis (DKA) is a life-threatening problem that affects people with diabetes. It occurs when the body starts breaking down fat at a r...ImageRead Article Now Book Mark Article Kidney disease Lactic acidosis AcidosisAcidosis 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 ...ImageRead Article Now Book Mark Article Metabolic acidosis Metabolic acidosisMetabolic acidosis is a condition in which there is too much acid in the body fluids.ImageRead Article Now Book Mark Article Methanol poisoning Methanol poisoningMethanol is a nondrinking type of alcohol used for industrial and automotive purposes. This article discusses poisoning from an overdose of methanol...Read Article Now Book Mark Article Renal tubular acidosis -- distal Renal tubular acidosis -- proximal Respiratory alkalosis (compensated) Salicylate toxicity (such as aspirin overdose) Ureteral diversionHigher-than-normal levels:Bartter syndrome Bartter syndromeBartter syndrome is a group of rare conditions that affect the kidneys.ImageRead Article Now Book Mark Article Burns BurnsBurns commonly occur by direct or indirect contact with heat, electric current, radiation, or chemical agents. Burns can lead to cell death, which c...ImageRead Article Now Book Mark Article Congestive heart failure Congestive heart failureHeart failure is a condition in which the heart is no longer able to pump oxygen-rich blood to the rest of the body efficiently. This causes symptom...ImageRead Article Now Book Mark Article Cushing syndrome Cushing syndromeCushing syndrome is a disorder that occurs when your body has a high level of the hormone cortisol.ImageRead Article Now Book Mark Article Dehydration DehydrationDehydration occurs when your body does not have as much water and fluids as it needs. Dehydration can be mild, moderate, or severe, based on how much...ImageRead Article Now Book Mark Article Excessive sweating Hyperaldosteronism HyperaldosteronismHyperaldosteronism is a disorder in which the adrenal gland releases too much of the hormone aldosterone into the blood. Hyperaldosteronism can be pr...ImageRead Article Now Book Mark Article Metabolic alkalosis AlkalosisAlkalosis is a condition in which the body fluids have excess base (alkali). This is the opposite of excess acid (acidosis).ImageRead Article Now Book Mark Article Respiratory acidosis (compensated) Syndrome of inappropriate diuretic hormone secretion (SIADH) Vomiting Delirium may also alter bicarbonate levels.DeliriumDelirium is sudden severe confusion due to rapid changes in brain function that can occur with physical or mental illness.ImageRead Article Now Book Mark Article Open ReferencesReferencesBansal A. Respiratory acidosis, respiratory alkalosis, and mixed acid-base disorders. In: Johnson RJ, Floege J, Tonelli M, eds. Comprehensive Clinical Nephrology. 7th ed. Philadelphia, PA: Elsevier; 2024:chap 15.Seifter JL. Acid-base disorders. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 104.AllVideoImagesTogBlood test - illustration Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.Blood testillustrationBlood test - illustration Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.Blood testillustration Tests for CO2 blood test CO2 blood testChloride test - bloodComprehensive metabolic panelBasic metabolic panelRelated Information Respiratory(Special Topic)Diabetic ketoacidosis(Condition)Acidosis(Condition)Diarrhea(Symptoms)Addison disease(Condition)Primary and secondary hyperaldosteronism(Condition)Cushing syndrome(Condition)Metabolic acidosis(Condition)Alkalosis(Condition)Delirium(Condition)Alzheimer disease - InDepth(In-Depth) Review Date: 5/19/2025 Reviewed By: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited. © 1997- All rights reserved. A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.Content is best viewed in IE9 or above, Firefox and Google Chrome browser.
CO2 blood testBicarbonate test; HCO3-; Carbon dioxide test; TCO2; Total CO2; CO2 test - serum; Acidosis - CO2; Alkalosis - CO2CO2 is carbon dioxide. This article discusses the laboratory test to measure the amount of carbon dioxide in the liquid part of your blood, called the serum.In the body, most of the CO2 is in the form of a substance called bicarbonate (HCO3-). Therefore, the CO2 blood test is really a measure of your blood bicarbonate level. How the Test is Performed A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.Blood is drawn from a veinVenipuncture is the collection of blood from a vein. It is most often done for laboratory testing.ImageRead Article Now Book Mark Article How to Prepare for the Test Many medicines can interfere with blood test results.Your health care provider will tell you if you need to stop taking any medicines before you have this test. DO NOT stop or change your medicines without talking to your provider first. How the Test will Feel You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn. Why the Test is Performed The CO2 test is most often done as part of an electrolyte or basic metabolic panel. Changes in your CO2 level may suggest that you are losing or retaining acidic fluid. This may cause an imbalance in your body's electrolytes.ElectrolyteElectrolytes are minerals in your blood and other body fluids that carry an electric charge. Electrolytes affect how your body functions in many ways...Read Article Now Book Mark Article CO2 levels in the blood are affected by kidney and lung function. The kidneys help maintain the normal bicarbonate levels. Normal Results The normal range is 23 to 29 milliequivalents per liter (mEq/L) or 23 to 29 millimoles per liter (mmol/L).Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.The example above shows the common measurement range of results for these tests. Some laboratories use different measurements or may test different specimens. What Abnormal Results Mean Abnormal levels may be due to the following problems:Lower-than-normal levels:Addison disease Addison diseaseAddison disease is a disorder that causes the adrenal glands to not produce enough hormones.ImageRead Article Now Book Mark Article Carbonic anhydrase inhibitors (used to treat glaucoma) Diarrhea DiarrheaDiarrhea is when you pass loose or watery stool.ImageRead Article Now Book Mark Article Ethylene glycol poisoning Ethylene glycol poisoningEthylene glycol is a colorless, odorless, sweet-tasting chemical. It is poisonous if swallowed. Ethylene glycol may be swallowed accidentally, or it...ImageRead Article Now Book Mark Article Ketoacidosis KetoacidosisDiabetic ketoacidosis (DKA) is a life-threatening problem that affects people with diabetes. It occurs when the body starts breaking down fat at a r...ImageRead Article Now Book Mark Article Kidney disease Lactic acidosis AcidosisAcidosis 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 ...ImageRead Article Now Book Mark Article Metabolic acidosis Metabolic acidosisMetabolic acidosis is a condition in which there is too much acid in the body fluids.ImageRead Article Now Book Mark Article Methanol poisoning Methanol poisoningMethanol is a nondrinking type of alcohol used for industrial and automotive purposes. This article discusses poisoning from an overdose of methanol...Read Article Now Book Mark Article Renal tubular acidosis -- distal Renal tubular acidosis -- proximal Respiratory alkalosis (compensated) Salicylate toxicity (such as aspirin overdose) Ureteral diversionHigher-than-normal levels:Bartter syndrome Bartter syndromeBartter syndrome is a group of rare conditions that affect the kidneys.ImageRead Article Now Book Mark Article Burns BurnsBurns commonly occur by direct or indirect contact with heat, electric current, radiation, or chemical agents. Burns can lead to cell death, which c...ImageRead Article Now Book Mark Article Congestive heart failure Congestive heart failureHeart failure is a condition in which the heart is no longer able to pump oxygen-rich blood to the rest of the body efficiently. This causes symptom...ImageRead Article Now Book Mark Article Cushing syndrome Cushing syndromeCushing syndrome is a disorder that occurs when your body has a high level of the hormone cortisol.ImageRead Article Now Book Mark Article Dehydration DehydrationDehydration occurs when your body does not have as much water and fluids as it needs. Dehydration can be mild, moderate, or severe, based on how much...ImageRead Article Now Book Mark Article Excessive sweating Hyperaldosteronism HyperaldosteronismHyperaldosteronism is a disorder in which the adrenal gland releases too much of the hormone aldosterone into the blood. Hyperaldosteronism can be pr...ImageRead Article Now Book Mark Article Metabolic alkalosis AlkalosisAlkalosis is a condition in which the body fluids have excess base (alkali). This is the opposite of excess acid (acidosis).ImageRead Article Now Book Mark Article Respiratory acidosis (compensated) Syndrome of inappropriate diuretic hormone secretion (SIADH) Vomiting Delirium may also alter bicarbonate levels.DeliriumDelirium is sudden severe confusion due to rapid changes in brain function that can occur with physical or mental illness.ImageRead Article Now Book Mark Article Open ReferencesReferencesBansal A. Respiratory acidosis, respiratory alkalosis, and mixed acid-base disorders. In: Johnson RJ, Floege J, Tonelli M, eds. Comprehensive Clinical Nephrology. 7th ed. Philadelphia, PA: Elsevier; 2024:chap 15.Seifter JL. Acid-base disorders. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 104.
