Which of the following is a hallmark feature of nephrotic syndrome?

• A. Proteinuria >3.5 g/day
• B. Hematuria
• C. Hypertension
• D. Oliguria

Answer: (A)

Heavy protein loss in the urine defines nephrotic syndrome. When the glomerular barrier is damaged, large proteins like albumin leak into the urine, and the amount filtered rises to nephrotic levels—typically more than about 3.5 grams per day. This massive proteinuria lowers the blood’s oncotic pressure, so fluid shifts into the interstitial space and edema develops. The liver senses the low oncotic pressure and increases lipoprotein synthesis, causing hyperlipidemia (and sometimes lipiduria). While other features such as hematuria, high blood pressure, or reduced urine output can occur in kidney disease, they are not the hallmark of nephrotic syndrome; hematuria is more characteristic of nephritic processes, and hypertension or oliguria are not defining components of nephrosis.