Acid-Base

Albumin-corrected Anion Gap Calculator

Anion gap adjusted for low albumin, which otherwise hides a gap metabolic acidosis.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

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Formula

AG + 2.5 * (4.0 - Albumin)

How it is used

• Because albumin is a major unmeasured anion, hypoalbuminemia will falsely lower the calculated anion gap.
• For every 1 g/dL drop in albumin below 4.0, the anion gap is falsely lowered by ~2.5 mEq/L.

• Always use the corrected anion gap in ICU patients, as hypoalbuminemia is nearly universal in critical illness.

Same formula as the app. Open it in the web app.

Related one-pagers

• ABG Interpretation in 6 Steps

Related calculators

• Delta Ratio
• Osmolar Gap
• Serum Osmolality
• Winters' Formula

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.