**Question:** All of the following cause high anion gap metabolic acidosis except

A. Diabetic ketoacidosis (DKA)
B. Acidosis due to respiratory failure
C. Acidosis due to lactic acidosis
D. Acidosis due to alkalosis

**Core Concept:** High anion gap acidosis is a type of acid-base disorder characterized by a significant difference between the measured and calculated anion gap. A high anion gap indicates the presence of unmeasured anions, such as ketones, lactate, or organic acids, that are not accounted for in the calculation.

**Why the Correct Answer is Right:** Option D, acidosis due to alkalosis, does not fit the definition of high anion gap acidosis because alkalosis is a condition of increased pH, which is not associated with unmeasured anions or a high anion gap.

**Why Each Wrong Option is Incorrect:**

**Option A (Diabetic Ketoacidosis):** Diabetic ketoacidosis (DKA) is a severe complication of uncontrolled diabetes mellitus, characterized by high anion gap acidosis due to the presence of unmeasured anions such as ketone bodies (acetoacetic acid and beta-hydroxybutyric acid), which are not accounted for in the anion gap calculation.

**Option B (Acidosis due to respiratory failure):** Acidosis due to respiratory failure results from impaired oxygenation and ventilation, leading to a compensatory alkalosis. This condition does not involve unmeasured anions or a high anion gap, making it inconsistent with high anion gap acidosis.

**Option C (Acidosis due to lactic acidosis):** Lactic acidosis is characterized by a low anion gap due to the presence of unmeasured anions (lactic acid), which are accounted for in the anion gap calculation. Hence, this option does not fit the definition of high anion gap acidosis.

**Clinical Pearl:** High anion gap acidosis is a critical clinical entity that requires prompt recognition and management, as it can progress to severe complications like DKA in diabetes mellitus and life-threatening electrolyte imbalances. A high anion gap acidosis can be managed by addressing the underlying cause (e.g., uncontrolled diabetes) and providing supportive care to maintain electrolyte balance and correct acidosis.