Anion Gap Calculator
Interpretation of the results of anion gap (albumin or non-albumin corrected)
| Anion Gap | Causes |
| High Anion Gap due to excess acid (AG >16) | Lactic acidosis |
| Ketoacidosis - starvation ketosis, alcohol or diabetic ketoacidosis | |
| Uremia | |
| Methanol or Ethanol | |
| Rhabdomyolysis | |
| Salicylate toxicity | |
| Isoniazid/Paraldehyde/Iron toxicity | |
| Normal Anion Gap due to renal or extra-renal (gastrointestinal) losses of bicarbonate (AG 8-16) | GI losses (enterocutaneous fistula, diarrhea, colostomy, ileostomy) |
| Isotonic saline infusion | |
| Renal tubular acidosis (type I or IV) | |
| Uteropelvic shunt | |
| Cholestyramine/Acetazolamide | |
| Addison's disease | |
| Low anion gap (<8) | Albumin (decreased unmeasured anions) |
| Calcium, magnesium, lithium (increased unmeasured cations) | |
| Laboratory error |
Interpretation of the results of delta ratioÂ
| Delta ratio | Interpretation |
| 0 to 0.4 | Hyperchloremic normal/non-anion gap acidosis |
| 0.4 to 1.0 | High anion gap acidosis and normal anion gap acidosis |
| 1 to 2 | High anion gap acidosis |
| >2 | High anion gap acidosis with co-existing metabolic alkalosis or fully compensated respiratory acidosis |
Interpretation of the results of delta gap (albumin or non-albumin corrected)
| Delta Gap | Interpretation |
| <18 | Concomitant non-anion gap metabolic acidosis |
| 18-30 | No additional metabolic perturbations |
| >30 | Concomitant metabolic alkalosis |
References
Oh MS, Carroll HJ. The anion gap. N Engl J Med. 1977 Oct 13;297(15):814-7. doi: 10.1056/NEJM197710132971507. PMID: 895822.
