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Albumin is a major unmeasured anion. In critically ill patients with hypoalbuminaemia (albumin < 4.0 g/dL), the raw AG is falsely low. Failure to correct can cause you to miss a HAGMA. Add 2.5 mEq/L to the AG for every 1 g/dL that albumin is below 4.0 g/dL.
| Delta-Delta < 1 |
| Delta-Delta 1 – 2 |
| Delta-Delta > 2 |
A patient with severe hypoalbuminaemia (albumin 1.5 g/dL) and lactic acidosis may have a raw AG of only 10 mEq/L — appearing "normal." After correction: AG = 10 + 2.5 × (4.0 − 1.5) = 16.25. This unmasked HAGMA changes the entire management approach.
The role of serum proteins in acid-base equilibria.
The delta-delta (ΔΔ) ratio in the diagnosis of mixed acid-base disorders.
The concept of the Anion Gap was first described by James Gamble in the 1940s using his "Gamblegram" — a visual representation of cation and anion balance in serum. The modern clinical application with the MUDPILES mnemonic was popularised through the work of nephrologists including Burton Rose and Theodore Post at Harvard Medical School.
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Curated insights • How it Works • Practical Pearls • Evidence Base
Albumin is a major unmeasured anion. In critically ill patients with hypoalbuminaemia (albumin < 4.0 g/dL), the raw AG is falsely low. Failure to correct can cause you to miss a HAGMA. Add 2.5 mEq/L to the AG for every 1 g/dL that albumin is below 4.0 g/dL.
| Delta-Delta < 1 |
| Delta-Delta 1 – 2 |
| Delta-Delta > 2 |
A patient with severe hypoalbuminaemia (albumin 1.5 g/dL) and lactic acidosis may have a raw AG of only 10 mEq/L — appearing "normal." After correction: AG = 10 + 2.5 × (4.0 − 1.5) = 16.25. This unmasked HAGMA changes the entire management approach.
The role of serum proteins in acid-base equilibria.
The delta-delta (ΔΔ) ratio in the diagnosis of mixed acid-base disorders.
The concept of the Anion Gap was first described by James Gamble in the 1940s using his "Gamblegram" — a visual representation of cation and anion balance in serum. The modern clinical application with the MUDPILES mnemonic was popularised through the work of nephrologists including Burton Rose and Theodore Post at Harvard Medical School.
