Reviewed by Rishi Desai, MD, MPH
Plasma anion gap
The anion gap is a value calculated from the difference in the measured cations (positively charged ions) and the measured anions (negatively charged ions) in serum, plasma, or urine. The normal value for anion gap is between 8-12 mEq/L. The equation to calculate anion gap is: anion gap = Na+ - (Cl- + HCO3-).