Which finding is most characteristic of nephrotic syndrome?

• A. Hyponatremia
• B. Edema
• C. Jaundice
• D. Hyperkalemia

Answer: (B)

Edema is the hallmark feature of nephrotic syndrome. The key sequence starts with heavy protein loss in the urine (proteinuria >3.5 g/day). Losing a lot of albumin lowers the plasma oncotic (colloid osmotic) pressure, so fluid shifts from the vascular compartment into the interstitial space, causing swelling. The body also responds to decreased circulating volume by retaining sodium and water, which can worsen the edema.

Nephrotic syndrome classically also features hypoalbuminemia and often hyperlipidemia; these underpin the edema and other findings, but the visible and most characteristic sign is the edema.

Hyponatremia, jaundice, and hyperkalemia are not defining features. Hyponatremia can occur in various settings due to fluid balance shifts, jaundice points to liver pathology, and hyperkalemia is more typical of renal failure or issues with potassium handling, not the primary problem in nephrotic syndrome.