Internal Medicine

Serum Anion Gap Calculator

Serum Anion Gap Calculator

Serum Anion Gap

Evaluates states of metabolic acidosis. Useful to determine if a patient’s metabolic acidosis has an elevated anion gap. Automatically calculates albumin correction and delta ratio.
Sodium (Na⁺)
mEq/L
Chloride (Cl⁻)
mEq/L
Bicarbonate (HCO₃⁻)
mEq/L
Albumin (Optional)
Patients with low albumin may have a lower baseline anion gap. Correction is recommended.
g/dL
—
Anion Gap
(mEq/L)
Delta Gap (ΔAG)
—
Delta Ratio (ΔAG/ΔHCO₃)
—
Anion Gap Metabolic Acidosis (MUDPILERS)
  • Methanol
  • Uremia
  • Diabetic ketoacidosis / alcoholic ketoacidosis
  • Paraldehyde
  • Isoniazid
  • Lactic acidosis
  • Ethanol / ethylene glycol
  • Rhabdomyolysis / renal failure
  • Salicylates
Non-Anion Gap Acidosis (HARDUPS)
  • Hyperalimentation
  • Acetazolamide
  • Renal tubular acidosis
  • Diarrhea
  • Ureteroenterostomy (or fistula)
  • Post-hypocapnia
  • Spironolactone
Metabolic Alkalosis (CLEVER PD)
  • Contraction
  • Licorice
  • Endocrine (Conn’s, Cushings, Bartter’s)
  • Vomiting
  • Excess alkali
  • Refeeding alkalosis
  • Post-hypercapnia
  • Diuretics
Respiratory Alkalosis (CHAMPS) – Speed up breathing
  • CNS disease
  • Hypoxia
  • Anxiety
  • Mechanical ventilators
  • Progesterone
  • Salicylates / sepsis
This calculator is intended for clinical decision support by medical professionals only. Management of an anion gap acidosis focuses on correcting the underlying cause.
Formulas Used:
  • Anion Gap = Na – (Cl + HCO3)
  • Albumin Corrected AG = AG + [2.5 × (4 – albumin)]
  • Delta Gap = Active AG – 12 (Assumed normal AG = 12)
  • Delta Ratio = Delta Gap / (24 – HCO3)
Reviewed by ·
Semahattin Serkan Sezer MD

Pulmonologist and Intensive Care Specialist specializing in clinical informatics and the development of evidence-based decision support tools for healthcare professionals.