A patient has a nasogastric tube on suction for 48 hours after surgery. Which electrolyte is most likely lost?

• A. Bicarbonate
• B. Potassium
• C. Calcium
• D. Phosphorus

Answer: (B)

Gastric suction drains the contents of the stomach, which include potassium along with hydrogen and chloride. Losing these gastric secretions over 48 hours can deplete the body's potassium stores, leading to hypokalemia. The stomach does not contribute a large amount of bicarbonate to gastric juice, so bicarbonate loss isn’t the main issue with suction. Calcium and phosphorus aren’t primarily lost in gastric secretions to a clinically significant degree. So potassium is the electrolyte most likely to be lost with nasogastric suction.