Which quartet best defines nephrotic syndrome?

• A. Hematuria with RBC casts, oliguria; HTN
• B. Hyperlipidemia only
• C. Heavy proteinuria (>3.5 g/day), hypoalbuminemia, edema, and hyperlipidemia
• D. Oliguria and azotemia

Answer: (C)

Nephrotic syndrome occurs when the glomerular filtration barrier leaks large amounts of protein into the urine, producing a distinctive pattern of systemic effects. The key quartet is heavy proteinuria (>3.5 g per day in adults), hypoalbuminemia, edema, and hyperlipidemia. The heavy proteinuria reflects the marked glomerular permeability to proteins. Loss of albumin reduces the circulating oncotic pressure, which promotes fluid shift into the interstitial spaces, causing edema. In response to hypoalbuminemia, the liver increases lipoprotein production, leading to hyperlipidemia. Edema is a hallmark consequence of these changes, and the lipid abnormalities help explain the metabolic aspect of the syndrome.

This combination helps distinguish nephrotic syndrome from nephritic scenarios, where you’d expect features like hematuria with red blood cell casts, oliguria, and hypertension due to inflammation and decreased kidney function. Simply having hyperlipidemia or oliguria with azotemia does not capture the full nephrotic picture.