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    Anion gap

    Calculate the anion gap from sodium, chloride, bicarbonate and (optionally) potassium.

    mmol/L
    mmol/L
    mmol/L
    mmol/L
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    For information only; not a substitute for medical advice. Data is neither sent nor stored.

    Formula

    AG = Na⁺ − (Cl⁻ + HCO₃⁻); with potassium: AG = (Na⁺ + K⁺) − (Cl⁻ + HCO₃⁻).

    Reference ranges

    • Without K⁺: 8–16 mmol/L
    • With K⁺: 10–20 mmol/L (method-dependent)

    Frequently asked questions

    Does albumin affect the anion gap?
    Yes. Every 10 g/L drop in albumin lowers the AG by about 2.5 mmol/L, so the AG is corrected in hypoalbuminemia.