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The AG is calculated from sodium, chloride, and bicarbonate, with potassium often omitted; interpretation should use the laboratory’s reference range. A high AG can reflect added organic acids or retained acids, while a normal-gap, hyperchloremic acidosis is associated with bicarbonate loss or impaired hydrogen-ion secretion. A low AG is uncommon and may relate to low albumin, paraproteinemias, certain cations, or measurement error. Because albumin contributes substantially to unmeasured anions, a low albumin concentration can lower the measured gap and should be considered in interpretation. Comparing the change in AG with the change in bicarbonate—the delta gap—can help identify a coexisting metabolic disorder. These patterns guide further assessment rather than establishing a cause on their own.