The anion gap is used to diagnose what type of problems?

• A. Anion gap measures blood glucose levels
• B. Anion gap assesses liver function
• C. Anion gap evaluates platelet function
• D. Anion gap helps diagnose acid-base problems

Answer: (D)

Anion gap is a calculation used in evaluating acid-base status. It estimates unmeasured anions in the blood and helps distinguish types of metabolic acidosis. You calculate it as sodium plus potassium minus chloride minus bicarbonate (some labs omit potassium). A higher-than-normal gap means there are extra unmeasured acids present—lactate, ketoacids, sulfates, or phosphates—pointing to high anion gap metabolic acidosis from causes like lactic acidosis, ketoacidosis, renal failure, or toxin ingestion. If the gap is normal, metabolic acidosis may be due to bicarbonate loss with chloride retention, such as diarrhea or certain renal tubular issues, without an increased gap. The anion gap isn’t used to assess blood glucose, liver function, or platelet function; those require other tests. It’s a key tool for interpreting acid-base disturbances and guiding further evaluation and treatment.