Anion Gap

Serum sodium level (Na):	mmol/L
(optional) Serum potassium level (K):	mmol/L
Serum chloride level (Cl):	mmol/L
Serum bicarbonate level (HCO₃):	mmol/L


Anion Gap =	mmol/L
Normal Anion Gap:

Anion gap = (Na + K) - (Cl + 
      [HCO3-]) 
(all units mmol/L)