INCREASED ANION GAP IN METABOLIC ALKALOSIS - ROLE OF PLASMA-PROTEIN EQUIVALENCY

THE plasma undetermined anion concentration (anion gap) is widely recognized as a valuable clinical tool.1,2 Although conventionally estimated as the difference between [Na+] or [Na+ + K+], on one hand, and [Cl– + HCO–3], on the other, the anion gap is, in fact, determined by the concentrations of unmeasured anions and unmeasured cations. Normally, about two thirds of the unmeasured anionic equivalency originates from the plasma proteins; the remainder is accounted for by plasma organic acids, phosphate and sulfate. When investigating the cause of an elevated anion gap, the clinician routinely seeks evidence for the presence. © 1979, Massachusetts Medical Society. All rights reserved.