In SIADH, which intervention is typically required?

• A. Increase fluid intake
• B. Fluid restriction
• C. Administer hypotonic IV fluids
• D. Administer diuretics

Answer: (B)

In SIADH, excess ADH makes the kidneys retain water, which dilutes the blood and lowers serum osmolality while the urine remains inappropriately concentrated. Because the problem is too much water relative to solutes, the most effective and typical intervention is fluid restriction—limiting free water intake to allow serum sodium to rise gradually and prevent further dilution. Increasing fluids or giving hypotonic IV fluids would worsen hyponatremia, and diuretics aren’t the first-line fix, though they may be used selectively in some cases to promote water excretion. In severe symptoms, more intensive treatment like hypertonic saline may be needed, but the standard approach centers on restricting fluids.