What is the normal range for the anion gap?

What is the normal range for the anion gap?

• A. 2–6 mEq/L
• B. 8–12 mEq/L
• C. 15–20 mEq/L
• D. 25–30 mEq/L

Answer: (B)

The normal range for the anion gap is 8–12 mEq/L. The anion gap is calculated as: Na − (Cl + HCO3). With typical values (Na about 140 mEq/L, Cl around 100–105 mEq/L, and bicarbonate about 24 mEq/L), the result is roughly 11, which falls in 8–12. This gap represents unmeasured anions such as albumin, phosphate, sulfate, and organic acids. A normal gap helps distinguish types of metabolic acidosis: a high anion gap suggests excess unmeasured acids (lactic, ketoacidosis, kidney failure, toxins), while a normal gap (hyperchloremic) points to bicarbonate loss with retained chloride. The other ranges listed do not align with typical lab values for the anion gap.

The normal range for the anion gap is 8–12 mEq/L. The anion gap is calculated as: Na − (Cl + HCO3). With typical values (Na about 140 mEq/L, Cl around 100–105 mEq/L, and bicarbonate about 24 mEq/L), the result is roughly 11, which falls in 8–12. This gap represents unmeasured anions such as albumin, phosphate, sulfate, and organic acids. A normal gap helps distinguish types of metabolic acidosis: a high anion gap suggests excess unmeasured acids (lactic, ketoacidosis, kidney failure, toxins), while a normal gap (hyperchloremic) points to bicarbonate loss with retained chloride. The other ranges listed do not align with typical lab values for the anion gap.