Bicarbonate (total CO2)
What it measures, and what changes the number.
This test measures the total carbon dioxide content of serum or plasma, most of which is present as bicarbonate. Bicarbonate is the main buffer the body uses to keep blood acidity balanced, so the result is used as an indicator of acid-base status.
It is part of the standard electrolyte and basic metabolic panels, read together with sodium, potassium and chloride, and often with glucose and creatinine. Sodium, chloride and bicarbonate together are used to calculate the anion gap.
Carbon dioxide escapes from a sample easily, so tubes that are underfilled, left uncapped or processed late can give a falsely low reading. A venous total CO2 on a chemistry panel is not the same measurement as the bicarbonate or pCO2 reported on an arterial blood gas. Labs may print it as CARBON DIOXIDE, CO2, Total CO2 or Bicarbonate.
Often read alongside: Sodium, Potassium, Chloride, Glucose, Creatinine