Nonanion gap metabolic acidosis can result from all of the following except:

Nonanion gap metabolic acidosis can result from all of the following except:

• A. Renal tubular acidosis
• B. Rapid saline expansion
• C. GI bicarbonate loss
• D. Lactic acidosis

Answer: (D)

Nonanion (normal) metabolic acidosis happens when bicarbonate is lost and chloride is retained, keeping the measured anion gap normal. Processes that cause this type include renal tubular acidosis, rapid saline expansion (hyperchloremic acidosis), and GI bicarbonate loss (like diarrhea), all by reducing bicarbonate while increasing chloride. Lactic acidosis, in contrast, adds lactate as an unmeasured anion and raises the anion gap. So lactic acidosis does not produce nonanion gap metabolic acidosis; it causes high anion gap metabolic acidosis.

Nonanion (normal) metabolic acidosis happens when bicarbonate is lost and chloride is retained, keeping the measured anion gap normal. Processes that cause this type include renal tubular acidosis, rapid saline expansion (hyperchloremic acidosis), and GI bicarbonate loss (like diarrhea), all by reducing bicarbonate while increasing chloride. Lactic acidosis, in contrast, adds lactate as an unmeasured anion and raises the anion gap. So lactic acidosis does not produce nonanion gap metabolic acidosis; it causes high anion gap metabolic acidosis.