A blood test provides valuable health information, often including carbon dioxide (CO2) levels. Understanding these levels offers insights into various bodily functions.
What CO2 (Bicarbonate) Represents in a Blood Test
When a blood test reports “CO2,” it primarily refers to the concentration of bicarbonate (HCO3-) in the blood. Bicarbonate is a dissolved form of carbon dioxide and is an electrolyte in the body. It plays a central role in maintaining the body’s acid-base balance, also known as pH regulation.
Bicarbonate acts as a buffer, neutralizing excess acids and bases to keep the blood’s pH within a narrow range of 7.35 to 7.45. This buffering system is essential for cells and organs to function properly. The kidneys and lungs work together to regulate bicarbonate levels; the kidneys excrete or reabsorb bicarbonate, while the lungs control carbon dioxide levels through breathing.
Interpreting Your CO2 (Bicarbonate) Levels
On a blood test report, the CO2 or bicarbonate level is given in milliequivalents per liter (mEq/L) or millimoles per liter (mmol/L). For adults, a normal bicarbonate level falls between 22 and 29 mEq/L. This range can vary slightly depending on the laboratory.
A bicarbonate level higher or lower than this normal range suggests difficulty maintaining acid-base balance. Elevated levels point to a condition called alkalosis, indicating too much base in the blood. Conversely, low bicarbonate levels indicate acidosis, meaning there is too much acid in the blood. A healthcare provider considers individual results within the context of a person’s overall health and other test findings.
What Causes Abnormal CO2 (Bicarbonate) Levels?
Abnormal bicarbonate levels can stem from various underlying health issues affecting the body’s acid-base balance. These imbalances can involve either an excess of acid or a deficiency of base, or vice versa.
High bicarbonate levels, a condition known as metabolic alkalosis. Causes include severe or prolonged vomiting, which leads to a loss of stomach acids and consequently increases the alkalinity of the blood. The use of certain diuretic medications, also known as water pills, can also cause elevated bicarbonate levels. Dehydration and certain kidney conditions that impair bicarbonate excretion are other factors.
Low bicarbonate levels, indicative of metabolic acidosis. Severe diarrhea can cause a loss of bicarbonate-rich fluids from the body. Kidney dysfunction can be a cause, as impaired kidneys struggle to excrete excess acid and regenerate bicarbonate. Diabetic ketoacidosis (DKA), a serious complication of diabetes, results in the body producing excessive acidic ketones, significantly lowering bicarbonate. Lactic acidosis, an accumulation of lactic acid often due to severe infection or shock, also reduces bicarbonate. Certain medications can also contribute to low bicarbonate.
Next Steps and When to Seek Medical Advice
Discovering an abnormal CO2 or bicarbonate level on a blood test does not automatically signify a serious health problem. Many factors, including temporary conditions or certain medications, can influence these levels.
It is always advisable to discuss blood test results with a healthcare provider. They can interpret the bicarbonate levels in the context of an individual’s medical history, current symptoms, and other diagnostic tests. This comprehensive approach helps determine if further testing or specific treatment is necessary to address any underlying imbalances.