## **Core Concept**
Non-proliferative glomerulonephritis (GN) refers to a category of kidney diseases characterized by glomerular injury without significant proliferation of glomerular cells. This category includes conditions like minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy. Proliferative GN, in contrast, involves the proliferation of glomerular cells and the infiltration of leukocytes.

## **Why the Correct Answer is Right**
The correct answer, **C. Post streptococcal glomerulonephritis (PSGN)**, is a type of proliferative glomerulonephritis. PSGN is characterized by the deposition of immune complexes in the glomeruli, leading to activation of complement, influx of inflammatory cells, and proliferation of glomerular cells. This condition typically follows a streptococcal infection and presents with hematuria, proteinuria, and often, renal insufficiency.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Minimal Change Disease is a classic example of a non-proliferative GN. It is characterized by the loss of foot processes of podocytes visible under electron microscopy but appears nearly normal under light microscopy. The disease presents with nephrotic syndrome and responds well to corticosteroids.
- **Option B:** Membranous Nephropathy is another form of non-proliferative GN. It involves the formation of immune complexes on the subepithelial side of the glomerular basement membrane, leading to thickening of the membrane. It typically presents with nephrotic syndrome.
- **Option D:** Focal Segmental Glomerulosclerosis (FSGS) is also a non-proliferative GN. It is characterized by sclerosis (scarring) of some glomeruli, which are otherwise normal. FSGS can present with proteinuria and sometimes nephrotic syndrome.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the differentiation between proliferative and non-proliferative GN is crucial for determining the prognosis and treatment plan. Proliferative GNs, like PSGN, may require more aggressive management, including immunosuppressive therapy, whereas non-proliferative GNs might focus on supportive care and specific treatments like corticosteroids or antiproteinuric agents.

## **Correct Answer:** C. Post streptococcal glomerulonephritis.