In metabolic acidosis, which bicarbonate value would you expect?

In metabolic acidosis, which bicarbonate value would you expect?

• A. Less than 22
• B. Greater than 26
• C. Between 22 and 26
• D. Equal to 30

Answer: (A)

In metabolic acidosis, there is a loss of bicarbonate or an excess of acid, so the bicarbonate buffer is used up and its level drops. Normal bicarbonate is about 22–26 mEq/L, so you’d expect HCO3− to be below 22 in metabolic acidosis. The body attempts to compensate by increasing ventilation to blow off CO2, with the approximate guidance of Winter’s formula: PaCO2 ≈ 1.5 × [HCO3−] + 8 ± 2. Values that stay normal or rise (such as 22–26 or 30) would not reflect this acidotic state.

In metabolic acidosis, there is a loss of bicarbonate or an excess of acid, so the bicarbonate buffer is used up and its level drops. Normal bicarbonate is about 22–26 mEq/L, so you’d expect HCO3− to be below 22 in metabolic acidosis. The body attempts to compensate by increasing ventilation to blow off CO2, with the approximate guidance of Winter’s formula: PaCO2 ≈ 1.5 × [HCO3−] + 8 ± 2. Values that stay normal or rise (such as 22–26 or 30) would not reflect this acidotic state.