View source for Normal anion gap metabolic acidosis

== Differential Diagnosis ==

* Mild [[AKI]], causing decreased ammonia excretion
* Lower GI [[diarrhea]]
* Fistulas
** Pancreatic
** Ileocutaneous
* [[Carbonic anhydrase inhibitors]]
* [[Renal tubular acidosis]] (RTA)
** Type 1 (hypokalemic distal)
** Type 2 (proximal)
** Type 4 (hyperkalemic distal)
* Ureteral diversion (e.g. ileal loop)
* Iatrogenic
** Dilution acidosis

== Investigations ==

* Serum electrolytes showing normal anion gap metabolic acidosis
* Urine anion gap (U<s>Na</s> + U<s>K</s> – U<s>Cl</s>)
** Difference between unmeasured anions (i.e. NH<s>4</s>^+^) and unmeasured cations
*** For most patients, approximates ammonium excretion
** If negative, suggests presence of ammonium (appropriate)
** If kidneys are responding properly, the UAG should be negative
** If defect in acid excretion, UAG should be positive
* Urine pH

[[Category:Nephrology]]
[[Category:Investigations]]