Question 1

What is a normal anion gap?

Accepted Answer

Normal anion gap is typically **12** (range 8–16, lab-dependent). It's calculated as `AG = Na − Cl − HCO₃`. In hypoalbuminemic patients, the AG must be corrected: corrected AG = AG + 2.5 × (4.0 − albumin).

Question 2

How do you interpret the delta ratio in metabolic acidosis?

Accepted Answer

Delta ratio = ΔAG / ΔHCO₃, where ΔAG = corrected AG − 12 and ΔHCO₃ = 24 − measured HCO₃.

- **<1**: high-anion-gap metabolic acidosis with concurrent non-AG metabolic acidosis
- **1–2**: pure HAGMA
- **>2**: HAGMA with concurrent metabolic alkalosis

Question 3

Why do you correct the anion gap for albumin?

Accepted Answer

Albumin is the largest unmeasured anion contributing to the AG. In hypoalbuminemia (ICU, cirrhosis, nephrotic syndrome), an apparently "normal" AG can mask a high-anion-gap metabolic acidosis. The correction adds **2.5 mEq/L per 1 g/dL drop in albumin below 4.0**.

Question 4

What causes a high anion gap metabolic acidosis?

Accepted Answer

Common causes (mnemonic GOLD MARK): **G**lycols (ethylene, propylene), **O**xoproline (chronic acetaminophen), **L**-lactate, **D**-lactate, **M**ethanol, **A**spirin, **R**enal failure (uremia), **K**etoacidosis (DKA, alcoholic, starvation).

Anion Gap + Delta-Delta

References

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