Continued nasogastric output results in loss of gastric secretions; what is the most common electrolyte abnormality?

• A. Hyperkalemia
• B. Hyponatremia
• C. Hypokalemia
• D. Hyperphosphatemia

Answer: (C)

Losing gastric secretions via a continuous NG drain mainly depletes hydrogen ions and chloride, creating metabolic alkalosis with volume depletion. The low volume stimulates aldosterone, which drives potassium loss in the kidneys. Alkalosis also causes potassium to shift into cells, lowering serum potassium. Together, these effects make hypokalemia the most common electrolyte abnormality with ongoing gastric drainage.