What is the hallmark feature of nephritic syndrome?

• A. Hematuria with red blood cell casts, plus hypertension and mild-to-moderate proteinuria
• B. Massive proteinuria without hematuria
• C. Pure oliguria without hematuria
• D. Nephrotic-range proteinuria with edema

Answer: (A)

In nephritic syndrome, the defining feature is inflammation of the glomeruli that leads to blood leakage into the urine. This shows up as hematuria with red blood cell casts in the urine, often along with hypertension and only mild-to-moderate proteinuria. The red blood cell casts form when RBCs pass through damaged glomeruli, mix with tubular proteins, and get molded in the tubules. Oliguria can occur because of reduced glomerular filtration rate, and edema is usually mild compared to the heavy swelling seen in nephrotic syndrome.

So the hallmark combination—hematuria with red blood cell casts, plus hypertension and mild-to-moderate proteinuria—best identifies nephritic syndrome. By contrast, massive proteinuria without blood points toward nephrotic syndrome, pure oliguria without hematuria suggests another form of kidney injury, and nephrotic-range proteinuria with edema also fits nephrotic syndrome.