Anion gap

Classify metabolic acidosis

Classify metabolic acidosis

Sodium (mmol/L)Chloride (mmol/L)Bicarbonate (mmol/L)Albumin (for correction) (g/dL)g/L ÷ 10 = g/dL. Corrects the gap for hypoalbuminaemia.

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Potassium is not included here. Reference ranges differ between laboratories.

Source: Figge J et al. Anion gap and hypoalbuminemia. Crit Care Med 1998;26(11):1807-1810.Open

Interpretation

Normal / low — ≤ 12 mmol/L — consider hyperchloraemic (normal-gap) acidosis.
Raised — > 12 mmol/L — high-anion-gap acidosis (lactate, ketones, renal failure, toxins).

Potassium is not included here. Reference ranges differ between laboratories.

These tools do not replace clinical judgement. Interpret the result in the context of the whole patient.