A 48-year-old man on ICU develops an unexplained metabolic acidosis. ABG: pH 7.25, PaCO2 3.2 kPa, HCO3 12 mmol/L, Na 140 mmol/L, K 4.0 mmol/L, Cl 105 ...

Question

A 48-year-old man on ICU develops an unexplained metabolic acidosis. ABG: pH 7.25, PaCO2 3.2 kPa, HCO3 12 mmol/L, Na 140 mmol/L, K 4.0 mmol/L, Cl 105 mmol/L. Lactate 1.5 mmol/L, glucose 5.5 mmol/L, urea 8 mmol/L, creatinine 100 µmol/L. Ketones are negative. What is the anion gap and what does it suggest?

Accepted Answer

Anion gap = 23 - suggesting an elevated anion gap metabolic acidosis from an unmeasured anion (e.g. toxic alcohol, salicylate, or pyroglutamic acid)

Answer

Anion gap = 12 (normal) - suggesting a non-anion-gap metabolic acidosis

Answer

Anion gap = 35 - suggesting massive ketoacidosis

Answer

Anion gap cannot be calculated from the given data

Answer

Anion gap = 8 - suggesting a low anion gap

uk-fficm MCQ (SBA): Anion Gap Metabolic Acidosis