In SIADH care, which fluid is used to flush enteral tubes?

• A. 0.9% sodium chloride
• B. 5% dextrose in water
• C. Lactated Ringer's
• D. Distilled water

Answer: (A)

In SIADH, the body holds onto too much water, diluting the blood sodium level. When flushing an enteral tube, you want to avoid adding free water that could further lower sodium. Using a fluid that is isotonic with blood and provides salt without introducing extra free water helps maintain sodium and intravascular volume. Normal saline (0.9% sodium chloride) fits this goal: it supplies sodium and chloride and stays close to plasma osmolality, reducing the risk of worsening hyponatremia. Fluids that add free water—like distilled water or 5% dextrose in water—can dilute sodium, and options like Lactated Ringer’s introduce additional electrolytes that may complicate the electrolyte balance. So, the best choice for flushing is isotonic saline.