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Biochemistry, Anion Gap.


Pandey DG1, Sharma S2.


StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019-.
2019 Apr 6.

Author information

Nova Southeastern University
Mery Fitzgerald Hospital


Using the results of the comprehensive metabolic panel (CMP), the anion gap is the difference between measured cations (positively charged ions like Na+ and K+) and measured anions (negatively charged ions like Cl- and HCO3-). There are three types: serum, plasma, and urine anion gaps. The most common application of the anion gap is classifying cases of metabolic acidosis, states of lower than normal blood pH. Specifically, classifying into either those that do and those that do not have unmeasured anions in the plasma. The human body is electrically neutral; therefore, in reality, does not have a true anion gap. The calculation then finds utility in exposing variations in that balance. However, changes in albumin and bicarbonate concentrations warrant specific attention.[1][2]

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