Causes of a Non-anion Gap Metabolic Acidosis. youtube.com/@jackcfchong Non-anion gap metabolic acidosis (NAGMA), also known as hyperchloremic metabolic acidosis, results from either the loss of bicarbonate or the excessive retention of chloride. The most common cause is gastrointestinal bicarbonate loss, frequently due to severe diarrhea, ileostomies, or fistulas. Another major category includes renal tubular acidosis (RTA), where the kidneys fail to either reabsorb bicarbonate (proximal RTA, Type 2) or excrete hydrogen ions (distal RTA, Types 1 and 4). Other causes include the rapid administration of large volumes of chloride-rich fluids (e.g., normal saline), certain medications like carbonic anhydrase inhibitors (e.g., acetazolamide), and hypoaldosteronism. A thorough patient history and laboratory evaluation are essential for accurate diagnosis.