What is the normal range for the anion gap in arterial blood gas analysis?

What is the normal range for the anion gap in arterial blood gas analysis?

• A. 6-12
• B. 8-14
• C. 10-14
• D. 12-16

Answer: (C)

The concept here is what the measured anion gap typically equals in a healthy individual. The anion gap is calculated as Na minus (Cl plus HCO3). In healthy adults, the gap is generally around 10–14 mEq/L, with small variation depending on the lab’s reference values and method. This range reflects the normal balance of measured cations and anions plus the contribution of unmeasured anions (like albumin, phosphates, sulfates). Among the given options, 10–14 mEq/L best captures this commonly cited normal range. The other ranges are either a bit too low or shifted higher than what is typically observed in standard ABG interpretation. Note that some labs cite 8–12 mEq/L or up to 16 mEq/L, but 10–14 is the range most often used in many exam resources.

The concept here is what the measured anion gap typically equals in a healthy individual. The anion gap is calculated as Na minus (Cl plus HCO3). In healthy adults, the gap is generally around 10–14 mEq/L, with small variation depending on the lab’s reference values and method. This range reflects the normal balance of measured cations and anions plus the contribution of unmeasured anions (like albumin, phosphates, sulfates). Among the given options, 10–14 mEq/L best captures this commonly cited normal range. The other ranges are either a bit too low or shifted higher than what is typically observed in standard ABG interpretation. Note that some labs cite 8–12 mEq/L or up to 16 mEq/L, but 10–14 is the range most often used in many exam resources.