What is the normal anion gap range when potassium is included?

• A. 10-20 mmol/L
• B. 7-16 mmol/L
• C. 12-24 mmol/L
• D. 5-15 mmol/L

Answer: (A)

An ion gap is the difference between measured cations and anions in the plasma, calculated with potassium included as AG = Na + K − Cl − HCO3. Because potassium is added to the cation side, the normal range shifts upward compared with the version that omits potassium.

The normal range when potassium is included is about 10–20 mmol/L. This reflects typical plasma Na, K, Cl, and HCO3− values; for example, Na around 140 and K around 4, with Cl about 100 and HCO3− about 24, gives an AG near 20, fitting within this range.