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DKA Acid-Base — RACP Adult Medicine MCQ

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EasyEndocrinologyDKA Acid-BaseRACP Adult Medicine

A 22-year-old woman with type 1 diabetes presents with Kussmaul breathing. ABG: pH 7.10, PaCO₂ 15 mmHg, PaO₂ 110 mmHg, HCO₃⁻ 5 mmol/L. Na⁺ 140, K⁺ 5.8, Cl⁻ 100 mmol/L. What is the acid-base disturbance?

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Correct answer: AMetabolic acidosis with respiratory compensation

Severe metabolic acidosis (low pH, very low HCO₃⁻) with appropriate respiratory compensation (Kussmaul breathing, low PaCO₂). Anion gap = 140 - (100 + 5) = 35 (elevated). Expected PaCO₂ = 1.5 × 5 + 8 = 15.5 (Winter formula), matching the actual PaCO₂ — confirming appropriate compensation without a mixed disorder. This is a high anion gap metabolic acidosis (DKA).

Reference: eTG Endocrine – 2024 – DKA; Winter's Formula