Which intervention is commonly recommended to slow cyst growth and preserve kidney function in PKD?

• A. Decrease fluids
• B. High-salt diet
• C. Increase fluids
• D. Avoid ACE inhibitors

Answer: (C)

Keeping well-hydrated is commonly recommended in PKD because high fluid intake lowers vasopressin levels. Vasopressin acts on receptors in the collecting ducts to raise cAMP inside cells, which stimulates cyst growth and fluid accumulation in cysts. By increasing fluids, you blunt this vasopressin-cAMP signaling, slowing the growth of cysts and helping preserve kidney function over time.

Decreasing fluids would raise vasopressin and could accelerate cyst expansion. A high-salt diet can worsen hypertension and kidney injury, not slow disease progression. ACE inhibitors are not something to avoid; they’re often used to Manage blood pressure and protect kidney function in PKD, so they wouldn’t be the recommended change.