Normal range for the serum anion gap is approximately:

Normal range for the serum anion gap is approximately:

• A. 8-12
• B. 2-6
• C. 20-28
• D. 30-40

Answer: (A)

The serum anion gap reflects the amount of unmeasured anions in the blood. It’s calculated as the difference between the major measured cation (sodium) and the sum of the major measured anions (chloride and bicarbonate). In healthy people this gap is typically about 8 to 12 mEq/L, with some laboratories accepting roughly 6 to 12. This range represents the balance of the ions that aren’t being measured directly. When the gap is much higher, it means there are extra unmeasured anions present—often due to metabolic acidosis from lactate, ketoacids, uremia, or toxins. Gaps around 20–28 or 30–40 are markedly abnormal and indicate a high anion gap acidosis. A very low gap is rare and not usually clinically meaningful. So the normal value sits around 8–12.

The serum anion gap reflects the amount of unmeasured anions in the blood. It’s calculated as the difference between the major measured cation (sodium) and the sum of the major measured anions (chloride and bicarbonate). In healthy people this gap is typically about 8 to 12 mEq/L, with some laboratories accepting roughly 6 to 12. This range represents the balance of the ions that aren’t being measured directly.

When the gap is much higher, it means there are extra unmeasured anions present—often due to metabolic acidosis from lactate, ketoacids, uremia, or toxins. Gaps around 20–28 or 30–40 are markedly abnormal and indicate a high anion gap acidosis. A very low gap is rare and not usually clinically meaningful. So the normal value sits around 8–12.