Evaluates states of metabolic acidosis.
Serum Anion Gap Calculator
For educational use only — not a substitute for clinical judgment.
Units
(For these monovalent ions, mEq/L ≡ mmol/L numerically.)
Formula
Many labs report AG without potassium.
mEq/L
mEq/L
mEq/L
mEq/L
g/dL
Anion gap
0.0
mEq/L
Albumin-corrected AG
0.0
AG + 2.5 × (4 − albumin)
Bicarbonate
24.0
mEq/L
Enter values to see interpretation.
How this tool interprets results
- AG (no K): Elevated if albumin-corrected AG > 12 mEq/L → suggests high anion gap metabolic acidosis (HAGMA).
- Normal AG acidosis (NAGMA): If HCO₃⁻ < ~22 mEq/L but corrected AG ≤ 12, consider hyperchloremic causes (e.g., GI bicarbonate loss, RTA).
- Low AG (< ~6): Consider hypoalbuminemia, paraproteinemia, bromide/lithium intoxication, or lab artifact.
- Albumin correction: AGcorr = AG + 2.5 × (4 − albumin[g/dL]).
References
- Kraut JA, Madias NE. Serum anion gap: its uses and limitations in clinical medicine. Clin J Am Soc Nephrol. 2007;2(1):162–174.
- Emmett M, Narins RG. Clinical use of the anion gap. Medicine (Baltimore). 1977;56(1):38–54.
- Berend K. Diagnostic use of base excess and anion gap. In: Comprehensive Clinical Nephrology, 6th ed. (Albumin-corrected AG ≈ AG + 2.5 × (4 − albumin)).
- Merck Manual Professional. Acid–Base Disorders: Anion Gap and Differential. Accessed 2025.
