Which of the following would be consistent with metabolic alkalosis?

Which of the following would be consistent with metabolic alkalosis?

• A. High PCO2, increased HCO3
• B. Low PCO2, increased HCO3
• C. High PCO2, decreased HCO3
• D. Low PCO2, decreased HCO3

Answer: (A)

Metabolic alkalosis shows an elevated bicarbonate (HCO3−) with an alkalemic pH. The body tries to compensate for this by retaining carbon dioxide, which is acidic, so the respiratory system reduces ventilation and raises the PCO2. Therefore, the pattern of high HCO3− together with high PCO2 fits metabolic alkalosis best. The other patterns don’t match: low PCO2 would indicate respiratory alkalosis or insufficient compensation, and decreased HCO3− points away from alkalosis (toward acidosis).

Metabolic alkalosis shows an elevated bicarbonate (HCO3−) with an alkalemic pH. The body tries to compensate for this by retaining carbon dioxide, which is acidic, so the respiratory system reduces ventilation and raises the PCO2. Therefore, the pattern of high HCO3− together with high PCO2 fits metabolic alkalosis best. The other patterns don’t match: low PCO2 would indicate respiratory alkalosis or insufficient compensation, and decreased HCO3− points away from alkalosis (toward acidosis).