Anion Gap Calculator

Calculate anion gap for acid-base disorder assessment with albumin correction and clinical interpretation

Medical Disclaimer: This tool is for educational purposes only. Always consult qualified healthcare professionals for patient care decisions.

Clinical Scenarios

Sodium (Na+)

mEq/L

Normal: 135-145 mEq/L

Chloride (Cl-)

mEq/L

Normal: 95-105 mEq/L

Bicarbonate (HCO3-)

mEq/L

Normal: 22-28 mEq/L

Albumin

g/dL

Normal: 3.5-5.0 g/dL

Serum Osmolality

mOsm/kg

Calculated Osmolality

mOsm/kg

What is Anion Gap?

The difference between measured cations and anions in serum, used to evaluate acid-base disorders.

Calculation:

AG = Na+ - (Cl- + HCO3-). Normal range is typically 8-16 mEq/L.

Albumin Correction:

Add 2.5 mEq/L for each 1 g/dL decrease in albumin below 4.0 g/dL.

Clinical Significance:

High AG suggests metabolic acidosis with unmeasured anions (organic acids, toxins).

High Anion Gap Causes:

MUDPILES - Methanol, Uremia, Diabetic ketoacidosis, Propylene glycol, Iron/Isoniazid, Lactic acidosis, Ethylene glycol, Salicylates.

Normal Gap Acidosis:

Diarrhea, ureterosigmoidostomy, carbonic anhydrase inhibitors, hyperalimentation.

Low Anion Gap:

Usually due to laboratory error, hypoalbuminemia, or paraproteinemia (multiple myeloma).

Clinical Correlation:

Always interpret with arterial blood gas, clinical history, and physical examination.