Hyponatremia due to increased water retention is commonly associated with which condition?

• A. Nephrotic syndrome
• B. Heart failure
• C. Liver cirrhosis
• D. Acute renal failure

Answer: (A)

Hyponatremia caused by increased water retention happens when the body retains more free water than solute, diluting the serum sodium. This often occurs in states where the kidneys sense reduced effective circulating volume and respond by conserving water through ADH (and sodium through RAAS).

In nephrotic syndrome, massive loss of albumin in the urine lowers plasma oncotic pressure. That makes fluid shift from the intravascular space into tissues, reducing effective circulating blood volume even though total body water is increased. The kidneys react to this perceived hypovolemia by releasing ADH and activating sodium and water-retaining mechanisms. The net effect is more water stored than sodium, leading to dilutional hyponatremia. While other conditions like heart failure or liver cirrhosis can also cause dilutional hyponatremia, the pattern in nephrotic syndrome—hypoalbuminemia-driven fluid shifts plus compensatory water retention—best explains the association described.