DKA Acid-Base — RACP Adult Medicine MCQ
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Correct answer: A — Metabolic 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