Reading an ABG in Diabetic Ketoacidosis

Endocrine · Question from the ATI RN Medical-Surgical 2023 Proctored Exam study set

Correct answer: B. pH 7.25, HCO3 15

Why this is the answer

DKA produces a metabolic acidosis: ketone bodies drive the pH down and consume bicarbonate, so both values drop together, exactly matching pH 7.25 with a low HCO3 of 15. Option A (pH 7.50, HCO3 28) shows an elevated pH and elevated bicarbonate — that's metabolic alkalosis, the opposite condition. Option C (pH 7.35, pCO2 40) is a completely normal, balanced ABG, not an acidotic one. Option D (pH 7.45, pCO2 35) also falls within normal limits and shows no acid-base disturbance at all.

The bigger concept

For any suspected metabolic disturbance, check whether pH and bicarbonate (HCO3) move in the same direction — both low points to metabolic acidosis, both high points to metabolic alkalosis. DKA is the classic teaching example of metabolic acidosis caused by ketone accumulation.

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