Electrolytes and acid–base

Anion gap (without potassium)

Calculate the serum anion gap with the no-potassium convention.

Intended population: Contemporaneous sodium, chloride and bicarbonate measurements in matching units.

Reference intervals vary by laboratory and assay. Albumin and unmeasured ions affect the gap; this version does not correct for albumin. A normal gap does not exclude acidosis or toxic exposure.

Sodium (mmol/L)

Chloride (mmol/L)

Bicarbonate / total CO₂ (mmol/L)

Sources and scoring references

National Kidney Foundation: High Anion Gap Metabolic Acidosis, Core Curriculum 2021 ↗

Implementation references reviewed October 28, 2026. Verify applicability and unusual or treatment-changing results against the linked references and local guidance.