What is the normal range for an anion gap?

What is the normal range for an anion gap?

• A. 0-4 mEq/L
• B. 8–12 mEq/L
• C. 16-20 mEq/L
• D. 40-60 mEq/L

Answer: (B)

An important idea here is that the anion gap estimates unmeasured anions in the blood and helps differentiate types of metabolic acidosis. It’s calculated as the difference between the main measured cation and the main measured anions: sodium minus (chloride plus bicarbonate). In healthy people, this gap is small and falls in a narrow reference range. The standard range most often cited in clinical practice and exams is about 8 to 12 mEq/L. Some labs or sources may round up a bit and cite up to around 16, but 8–12 mEq/L is the typical target for what’s considered normal. Knowing this helps you interpret acid-base disorders: a high anion gap suggests accumulation of unmeasured anions (like lactate, ketoacids, or toxins), while a normal gap with acidosis points toward a bicarbonate loss with chloride replacement (hyperchloremic acidosis). The other provided ranges are outside the commonly accepted normal window, so they don’t fit as the normal range.

An important idea here is that the anion gap estimates unmeasured anions in the blood and helps differentiate types of metabolic acidosis. It’s calculated as the difference between the main measured cation and the main measured anions: sodium minus (chloride plus bicarbonate). In healthy people, this gap is small and falls in a narrow reference range. The standard range most often cited in clinical practice and exams is about 8 to 12 mEq/L. Some labs or sources may round up a bit and cite up to around 16, but 8–12 mEq/L is the typical target for what’s considered normal.

Knowing this helps you interpret acid-base disorders: a high anion gap suggests accumulation of unmeasured anions (like lactate, ketoacids, or toxins), while a normal gap with acidosis points toward a bicarbonate loss with chloride replacement (hyperchloremic acidosis). The other provided ranges are outside the commonly accepted normal window, so they don’t fit as the normal range.