Metabolic acidosis without an anion gap can be seen in a number of conditions.

Conditions with low-normal or decreased serum potassium

(1) intestinal bicarbonate loss (secretory diarrhea, high-output fistula)

(2) pancreatic/biliary drainage

(3) ureteroenteric fistula or urinary intestinal diversion

(4) type 1 or 2 renal tubular acidosis

(5) carbonic anhydrase inhibitor

(6) toluene intoxication

(7) D-lactic acidosis

(8) resolving diabetic ketoacidosis


Conditions with high-normal or elevated serum potassium

(1) hyperkalemia distal RTA

(2) chronic kidney disease

(3) hyporeninemic hypoaldosteronism

(4) Gordon syndrome (pseudohypoaldosteronism type 2)

(5) high ileostomy output

(6) decreased distal sodium delivery

(7) exogenous acid (hydrochloric acid, TPN, calcium chloride)

(8) drug-related (NSAIDS, triamterine, trimethoprin, amiloride, heparin, pentamide, spironolactone, ARB, ACE inhibitor)


Other causes of non-anion gap metabolic acidosis:

(1) infusion of normal saline

(2) chronic hyperventilation

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