Complex sentence: In patients with a normal anion gap the drop in HCO 3 − is the primary pathology, and since there is only one other major buffering anion, must be compensated for almost completely by an increase in Cl −.
Split into simpler sentences: In patients with a normal anion gap the drop in HCO 3 − is the primary pathology. Since there is only one other major buffering anion, it must be compensated for almost completely by an increase in Cl −.