Which electrolyte imbalance is commonly associated with fistula output?

• A. Hyperkalemia
• B. Hypokalemia
• C. Hypernatremia
• D. Hypocalcemia

Answer: (C)

Fistula output can drain large volumes of fluid from the GI tract, so the body loses a lot of water along with electrolytes. If water replacement lags behind these losses, the remaining serum becomes more concentrated, raising the sodium level. This free-water deficit with external drainage makes hypernatremia a common electrolyte imbalance seen with fistula output, especially with high-output fistulas.

In this context, hyperkalemia or hypokalemia aren’t the characteristic changes tied to fistula drainage, and calcium disturbances aren’t the primary pattern associated with the fluid losses from fistulas. The key idea is that significant water loss leads to concentrated serum sodium, hence hypernatremia.