AG = Na+ - (Cl- + HCO3-)
ΔAG = AG - 12
ΔRatio = ΔAG / (24 - HCO3-)
Normal range: 8~16 mmol/L
The anion gap (AG) is the difference between the total number of cations and anions in serum that are commonly measured.
AG is an important indicator to assist in judging metabolic acidosis and various mixed acid-base imbalances.