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Electrolytes & Minerals

Bicarbonate (CO₂ content)

Normal range 22–29 mEq/L (22–29 mmol/L SI). Specimen: Serum or plasma.

Also known as: HCO3, total CO2, carbon dioxide content.

22–29 mEq/LCritical: read below

Reference range

ConventionalmEq/L
2229
SImmol/L
2229
SpecimenSerum or plasma
Conventional range22–29 mEq/L
SI range22–29 mmol/L
Conversion factor×1 (conventional → SI)
Critical value< 15 or > 40 mmol/L
PanelElectrolytes & Minerals

Convert any Bicarbonate (CO₂ content) result between units on the unit converter.

What is the normal range for Bicarbonate (CO₂ content)?

The standard teaching reference range for Bicarbonate (CO₂ content) is 22–29 mEq/L in conventional units, or 22–29 mmol/L in SI units. This value is measured in serum or plasma.

A commonly taught critical (panic) value is < 15 or > 40 mmol/L. Critical results are reported to the provider immediately under your facility's policy.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Bicarbonate (CO₂ content)

  • Metabolic alkalosis
  • Vomiting or gastric suction
  • Compensation for respiratory acidosis

Below the range

Common causes of a low Bicarbonate (CO₂ content)

  • Metabolic acidosis (DKA, lactic acidosis)
  • Diarrhea
  • Renal failure
  • Compensation for respiratory alkalosis

At the bedside

Nursing considerations

  • The venous CO₂ estimates bicarbonate; confirm acid–base status with an ABG when unclear.

Study aid

Your notes on Bicarbonate (CO₂ content)

Same panel

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