Albumin-Corrected Anion Gap — Free Online Calculator
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Anion Gap
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Albumin-Corrected Anion Gap
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About This Calculator
The Albumin-Corrected Anion Gap adjusts the standard anion gap for hypoalbuminemia, which is common in hospitalized patients. Each 1 g/dL decrease in albumin below 4.0 g/dL reduces the anion gap by approximately 2.5 mEq/L, potentially masking an elevated anion gap acidosis. The Delta-Delta ratio (Delta Gap) further classifies mixed acid-base disorders by comparing the change in anion gap to the change in bicarbonate.
Formula
Interpretation
| Parameter | Interpretation |
|---|---|
| Corrected AG ≤ 12 | Normal anion gap |
| Corrected AG > 12 | Anion gap metabolic acidosis |
| Delta-Delta < 1 | Concurrent non-AG metabolic acidosis |
| Delta-Delta 1 – 2 | Pure AG metabolic acidosis |
| Delta-Delta > 2 | Concurrent metabolic alkalosis |
References
Frequently Asked Questions
Why correct the anion gap for albumin?
Albumin is the major unmeasured anion in the anion gap. Normal AG of 12 assumes albumin of 4.0 g/dL. In hypoalbuminemia (common in hospitalized patients), the uncorrected AG may appear normal even when an anion gap acidosis is present. Each 1 g/dL drop in albumin lowers the AG by ~2.5 mEq/L.
How does the delta-delta ratio help diagnose mixed acid-base disorders?
The delta-delta compares the rise in AG above normal to the fall in bicarbonate below normal. In a pure AGMA, these changes should be equal (ratio ~1). A ratio <1 suggests concurrent non-AG metabolic acidosis (extra bicarbonate loss). A ratio >2 suggests concurrent metabolic alkalosis (bicarbonate higher than expected).
What are common causes of anion gap metabolic acidosis?
The mnemonic MUDPILES covers the major causes: Methanol, Uremia, Diabetic ketoacidosis, Propylene glycol, Isoniazid/Iron, Lactic acidosis, Ethylene glycol, and Salicylates. Of these, lactic acidosis and DKA are the most common. The corrected AG is essential for diagnosis when albumin is low.
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⚠ Medical Disclaimer
This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.