Which of the following is a likely cause of a high anion gap metabolic acidosis in a non-diabetic patient?

• A. Lactic acidosis
• B. Hypercalcemia
• C. Hypokalemia
• D. Hyperlipidemia

Answer: (A)

A high anion gap metabolic acidosis happens when unmeasured anions accumulate in the blood. The most common and classic example is lactic acidosis, where lactate builds up from anaerobic metabolism due to poor tissue oxygen delivery or perfusion (think sepsis, shock, severe hypoxia, or significant blood loss). Lactate carries a negative charge that isn’t counted in the usual electrolyte measurements, so the difference Na minus (Cl plus HCO3) widens, creating a large anion gap.

In a non-diabetic patient, lactic acidosis is still a leading cause because it doesn’t depend on diabetes status. It reflects a state of relative tissue hypoxia or impaired clearance, rather than insulin deficiency or diabetic ketoacidosis.

The other options don’t typically raise the anion gap. Hypercalcemia isn’t driven by unmeasured anions and doesn’t produce a high anion gap metabolic acidosis. Hypokalemia is an electrolyte disturbance that can accompany acidosis but isn’t the cause of a high anion gap. Hyperlipidemia doesn’t generate the unmeasured anions that widen the gap in this context.