Anion Gap Calculator
Calculate anion gap using serum electrolyte values. Includes delta gap and albumin-corrected anion gap for accurate metabolic acidosis assessment.
Anion Gap Results
Corrected Values
Clinical Interpretation
Delta Gap Analysis
Enter bicarbonate and anion gap values to calculate delta gap.
Anion Gap Interpretation
- Normal: 8-12 mEq/L - No anion gap metabolic acidosis
- Elevated: >12 mEq/L - Anion gap metabolic acidosis
- Low: <8 mEq/L - Hypoalbuminemia or other causes
- Corrected for Albumin: More accurate in hypoalbuminemia
Causes of Elevated Anion Gap
- MUDPILES: Methanol, Uremia, DKA, Paraldehyde, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates
- Lactic Acidosis: Shock, sepsis, hypoxia
- DKA: Diabetic ketoacidosis
- Renal Failure: Uremic acidosis
Formulas
- Anion Gap: Na+ - (Cl- + HCO3-)
- With K+: (Na+ + K+) - (Cl- + HCO3-)
- Albumin Corrected: AG + 2.5 × (4.0 - Albumin)
- Delta Gap: (Measured AG - 12) / (24 - Measured HCO3-)
Frequently Asked Questions
What is anion gap?
The anion gap is the difference between measured cations (sodium) and measured anions (chloride and bicarbonate) in the blood. It's calculated using the formula: Anion Gap = Na+ - (Cl- + HCO3-). The normal range is typically 8-12 mEq/L.
How do you calculate anion gap?
Formula: Anion Gap = Na+ - (Cl- + HCO3-)
Example: Na+ = 140, Cl- = 105, HCO3- = 24 → AG = 140 - (105 + 24) = 11 mEq/L
What is a normal anion gap?
A normal anion gap is between 8-12 mEq/L. Values may vary slightly between laboratories. Some sources use 8-16 mEq/L as the normal range.
What does a high anion gap mean?
A high anion gap (>12 mEq/L) indicates the presence of metabolic acidosis with an increased concentration of unmeasured anions. Causes include lactic acidosis, ketoacidosis, renal failure, and toxic ingestions (MUD PILES).
What is the delta gap?
The delta gap compares the change in anion gap to the change in bicarbonate. Delta Gap = (Measured AG - 12) / (24 - Measured HCO3-). A delta gap < 0.4 suggests a mixed disorder, while > 1.2 indicates a metabolic alkalosis component.
What is albumin-corrected anion gap?
Albumin is a negatively charged protein that contributes to the anion gap. In hypoalbuminemia, the anion gap may appear falsely normal. The corrected anion gap adds 2.5 mEq/L for every 1 g/dL decrease in albumin below 4.0 g/dL.
Should potassium be included in anion gap?
Traditionally, potassium is excluded from the anion gap calculation. Some clinicians include potassium (K+) in the formula: AG = (Na+ + K+) - (Cl- + HCO3-). This calculator includes both options.
When should I use anion gap?
Anion gap is used to evaluate metabolic acidosis, differentiate between high and normal anion gap acidosis, monitor treatment response, and assess acid-base disorders in critically ill patients.