Carbon Dioxide Total
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Decription: Carbon Dioxide, Total, Formal name: Bicarbonate. Also known as: Total CO2, TCO2, Bicarb
The total CO2, (Carbon Dioxide, Total) test measures the total amount of carbon dioxide in the blood, mainly in the form of bicarbonate (HCO3-).
Bicarbonate is an electrolyte excreted and reabsorbed by the kidneys. It is used by the body to maintain the body’s acid-base balance (pH) and also maintain electrical neutrality at the cellular level together with sodium, potassium, and chloride.
This tests helps diagnose an electrolyte imbalance, acidosis or alkalosis as the result of a disease. It is prescribed in after symptoms such as weakness, confusion, prolonged vomiting, or respiratory distress that could indicate an electrolyte imbalance or acidosis or alkalosis.
The bicarbonate test is usually ordered along with sodium, potassium, and chloride as part of an electrolyte panel. It may be ordered as part of a routine exam or to help evaluate a chronic illness such as kidney disease and hypertension, and to monitor the effectiveness of treatment.
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the test
To determine Bicarbonate concentration in blood.
When an acid-base imbalance is foreseen, an electrolyte panel and blood gases may be ordered to evaluate the severity of the imbalance, determine whether it is from respiratory origin or metabolic, and monitor its treatment until the acid-base balance is restored.
Reference range values
Carbon Dioxide, Total: 21 – 31 mmol/L
Sodium: 135-144 mmol/L
Potassium: 3.3 - 5.1 mmol/L
Chloride: 99 – 107 mmol/L
Possible causes of a low bicarbonate level include:
• Addison’s disease
• Chronic diarrhea
• Diabetic ketoacidosis
• Metabolic acidosis
• Kidney disease
• Ethylene glycol or methanol poisoning
• Salicylate (aspirin) overdose
Possible causes of high levels are:
• Severe vomiting
• Lung diseases
• Cushing’s syndrome
• Conn’s syndrome
• Metabolic alkalosis