Anion gap

FREE

Na − (Cl + HCO₃) from an electrolyte panel.

Note

Anion gap = 140 − (104 + 24) = 12 mmol/L. The expected range depends on the analyser; many labs quote about 8–12 mmol/L without potassium.

Reference: Anion gap = Na⁺ − (Cl⁻ + HCO₃⁻). For learning only. Reference intervals vary by laboratory, method and patient group; results are interpreted by qualified professionals with the clinical picture.

Formula

Anion gap = Na − (Cl + HCO₃), all mmol/L

Worked example

Na 140, Cl 104, HCO₃ 24 → 12 mmol/L

Limitations

Reference ranges depend on the analyser and whether potassium is included; low albumin lowers the gap.

For learning only. Reference intervals vary by laboratory, method and patient group; results are interpreted by qualified professionals with the clinical picture.