← Back to All Calculators
Shortcode 105 — Laboratory
Anion Gap Calculator
Calculates standard & albumin-corrected anion gap, delta-delta ratio, and respiratory compensation — with MUDPILES/HARDUPS mnemonics.
Required Inputs
mEq/L — normal 135–145
Enter a valid sodium value (100–180)
mEq/L — normal 98–106
Enter a valid chloride value (60–140)
mEq/L — normal 22–26
Enter a valid bicarbonate value (1–50)
g/dL — default 4.0; correct if hypoalbuminemic
Optional Inputs
mg/dL — for phosphate correction
mmHg — compare to Winter’s expected
Results
Anion Gap
—
mEq/L (normal 8–12)
—
Corrected AG
—
mEq/L (albumin-adjusted)
—
Delta Gap
—
AG_corr − 12
—
Delta-Delta Ratio
—
(AG−12) / (24−HCO₃)
—
Expected PaCO₂
—
mmHg (Winter’s / Comp.)
—
Acid-Base Pattern
—
Primary diagnosis
—
Clinical Interpretation
—
Respiratory Compensation (Winter’s Formula / Metabolic Alkalosis)
—
MUDPILES — HAGMA Causes
- M Methanol
- U Uremia
- D Diabetic ketoacidosis
- P Propylene glycol / Paracetamol
- I Isoniazid / Iron
- L Lactic acidosis
- E Ethylene glycol
- S Salicylates
HARDUPS — NAGMA Causes
- H Hyperalimentation
- A Addison’s disease
- R Renal tubular acidosis
- D Diarrhea
- U Ureteroenteric fistula
- P Pancreatic fistula
- S Spironolactone / Saline excess
Formulas Used
AG = Na - (Cl + HCO3) [Normal: 8-12 mEq/L] AG_corr = AG + 2.5 x (4.0 - Albumin) [Albumin correction] Phosphate corr: AG_corr - 0.5 x (Phos_mmol - 1.0) [if entered] where Phos_mmol = Phos(mg/dL) / 3.1 Delta gap = AG_corr - 12 Delta-delta = (AG_corr - 12) / (24 - HCO3) <0.4 => Pure NAGMA 0.4-0.8 => Mixed HAGMA + NAGMA 1.0-2.0 => Pure HAGMA >2.0 => HAGMA + Metabolic alkalosis Winter's (metabolic acidosis, HCO3 <22): Expected PCO2 = 1.5 x HCO3 + 8 (+/-2) Metabolic alkalosis comp. (HCO3 >26): Expected PCO2 = 0.7 x HCO3 + 21 (+/-2)
Medical Disclaimer
This calculator is for educational and clinical decision-support purposes only. Values must be interpreted in the context of the full clinical picture. Always correlate with arterial blood gas results and consult appropriate medical references. Not a substitute for professional medical judgment.
