Normal anion gap acidosis

In renal physiology, normal anion gap acidosis, and less precisely non-anion gap acidosis, is an acidosis that is not accompanied by an anion gap.

Differential diagnosis
The differential diagnosis of normal anion gap acidosis is relatively short (when compared to the differential diagnosis of acidosis):
 * Hyperalimentation
 * Acetazolamide and other carbonic anhydrase inhibitors
 * Renal tubular acidosis
 * Diarrhea
 * Ureteroenteric fistula - an abnormal connection (fistula) between a ureter and the gastrointestinal tract
 * Pancreaticoduodenal fistula - an abnormal connection between the pancreas and duodenum

It can be remembered with the mnemonic HARD-UP.

Causes
The most common cause of normal anion gap acidosis is diarrhea.