Which statement about treating hypovolemic hyponatremia is true?

Which statement about treating hypovolemic hyponatremia is true?

• A. It should be avoided because it worsens hyponatremia
• B. It is the treatment of choice to restore volume
• C. It should be replaced with hypertonic saline
• D. It should be treated with fluid restriction alone

Answer: (B)

The key idea is that the priority in hypovolemic hyponatremia is to restore circulating volume. When there is true loss of salt and water, effective arterial volume drops, ADH is released, and water is retained, which keeps hyponatremia present. Giving isotonic saline (0.9% NaCl) supplies both sodium and water to re-expand the intravascular volume, improves renal perfusion, suppresses ADH, and promotes excretion of free water. This approach corrects the underlying deficit and allows the serum sodium to rise gradually as the kidneys regain function. Fluid restriction alone won’t address the volume deficit and could worsen perfusion. Hypertonic saline is reserved for severe, life-threatening symptoms (like seizures or coma), not for routine volume repletion in typical hypovolemic hyponatremia.

The key idea is that the priority in hypovolemic hyponatremia is to restore circulating volume. When there is true loss of salt and water, effective arterial volume drops, ADH is released, and water is retained, which keeps hyponatremia present. Giving isotonic saline (0.9% NaCl) supplies both sodium and water to re-expand the intravascular volume, improves renal perfusion, suppresses ADH, and promotes excretion of free water. This approach corrects the underlying deficit and allows the serum sodium to rise gradually as the kidneys regain function.

Fluid restriction alone won’t address the volume deficit and could worsen perfusion. Hypertonic saline is reserved for severe, life-threatening symptoms (like seizures or coma), not for routine volume repletion in typical hypovolemic hyponatremia.