11 In contrast to the anion gap shown in equation 3 above, the physicochemical model emphasizes that all cation and anion concentrations must balance, according to the laws of electroneutrality.

1 The popularity and beauty of the anion-gap calculation derive largely from the fact that the equation is conceptually simple to understand and interpret and often gives very helpful information ...

and the major measured anions (chloride and bicarbonate), as described by the following equation: The normal anion gap ranges from 3 to 13 mEq/L, with a mean of about 7 to 10 mEq/L. It is composed ...