Anion gap = Na⁺ − (Cl⁻ + HCO₃⁻)
Use serum sodium, chloride, and bicarbonate values
Normal anion gap is typically about 8–12 mEq/L without potassium
If potassium is included: Anion gap = (Na⁺ + K⁺) − (Cl⁻ + HCO₃⁻)
Potassium is usually omitted in routine calculation
Calculate by subtracting the sum of chloride and bicarbonate from sodium
Result is reported in mEq/L or mmol/L
Correct for albumin if needed: corrected AG = measured AG + 2.5 × (4.0 − serum albumin in g/dL)