Which ABG finding is most consistent with metabolic alkalosis?

Which ABG finding is most consistent with metabolic alkalosis?

• A. Decreased bicarbonate
• B. Decreased PO2
• C. Increased PCO2
• D. Increased bicarbonate

Answer: (D)

Metabolic alkalosis is defined by an elevation in bicarbonate that raises the blood pH. The defining ABG finding is an increased bicarbonate level, since the alkalosis originates from excess bicarbonate or loss of hydrogen ions. The body may compensate by hypoventilating to raise CO2 (so PCO2 can be elevated), but this is a secondary adjustment rather than the primary abnormality. Decreased bicarbonate would indicate metabolic acidosis, not alkalosis. Decreased PO2 points to hypoxemia, which isn’t specific to alkalosis. While an increased PCO2 can appear with respiratory compensation, the most characteristic and direct finding in metabolic alkalosis is increased bicarbonate.

Metabolic alkalosis is defined by an elevation in bicarbonate that raises the blood pH. The defining ABG finding is an increased bicarbonate level, since the alkalosis originates from excess bicarbonate or loss of hydrogen ions. The body may compensate by hypoventilating to raise CO2 (so PCO2 can be elevated), but this is a secondary adjustment rather than the primary abnormality.

Decreased bicarbonate would indicate metabolic acidosis, not alkalosis. Decreased PO2 points to hypoxemia, which isn’t specific to alkalosis. While an increased PCO2 can appear with respiratory compensation, the most characteristic and direct finding in metabolic alkalosis is increased bicarbonate.