Anion Gap Calculator (Albumin-Corrected)
Calculate the serum anion gap, with optional albumin correction, to evaluate a metabolic acidosis and decide between a high-anion-gap and normal-anion-gap differential.
When to use it
Use in any suspected metabolic acidosis. Correct for hypoalbuminemia (each 1 g/dL fall in albumin lowers the measured gap by about 2.5 mmol/L), which otherwise masks a true high-gap acidosis.
Formula
Anion gap = sodium - (chloride + bicarbonate). Corrected gap = anion gap + 2.5 x (4.4 - albumin in g/dL) (Figge 1998).
Category
Acid-Base & Electrolytes
References
- Kraut JA et al. Serum anion gap: its uses and limitations in clinical medicine. Clin J Am Soc Nephrol. 2007;2:162-74. PMID: 17699401
- Figge J et al. Anion gap and hypoalbuminemia. Crit Care Med. 1998;26:1807-10. PMID: 9824071
About NephroMind
This calculator is part of NephroMind, a free clinical decision-aid platform from the Arab Society of Nephrology and Renal Transplantation (ASNRT) — over 128 bedside nephrology calculators plus a renal drug-dosing database, coded by a practicing transplant nephrologist.