Nephrotic syndrome is the hallmark of the following primary kidney diseases, except:
**Core Concept**
Nephrotic syndrome is characterized by a triad of massive proteinuria (>3.5 g/24 hours), hypoalbuminemia, and edema. It is primarily caused by damage to the glomerular filtration barrier, leading to the loss of large amounts of albumin and other proteins in the urine.
**Why the Correct Answer is Right**
The correct answer is **C.** Focal segmental glomerulosclerosis (FSGS) is a common cause of nephrotic syndrome, accounting for approximately 25-30% of cases. FSGS is characterized by the scarring and sclerosis of glomeruli, leading to the disruption of the glomerular filtration barrier and the loss of albumin in the urine.
**Why Each Wrong Option is Incorrect**
* **Option A:** Minimal change disease (MCD) is a common cause of nephrotic syndrome, particularly in children. It is characterized by the normal appearance of glomeruli on light microscopy but the presence of podocyte foot process effacement on electron microscopy. MCD is not an exception to the hallmark of nephrotic syndrome.
* **Option B:** Membranous nephropathy is another common cause of nephrotic syndrome, often associated with autoimmune disorders or infections. It is characterized by the thickening of the glomerular basement membrane, leading to the loss of albumin in the urine. Membranous nephropathy is not an exception to the hallmark of nephrotic syndrome.
* **Option D:** No option D provided. A correct question would provide all options.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the clinical presentation of nephrotic syndrome can vary widely, and a thorough evaluation, including renal biopsy, is often necessary to determine the underlying cause.
**Correct Answer:** C. FSGS is not a hallmark of nephrotic syndrome, but rather a common cause of it.