**Question:** Condition which presents as -nephritic syndrome with features of loss of foot processes on electron microscopy and poor response to corticosteroid therapy is: March 2012

**Correct Answer:** D. Membranous Nephropathy

**Core Concept:** Nephritic Syndrome

Nephritic syndrome refers to a group of clinical conditions characterized by acute kidney injury, proteinuria, hematuria, and hypertension. These conditions can lead to acute kidney damage if left untreated, potentially progressing to end-stage renal disease. The pathophysiology of nephritic syndrome is complex and involves various etiologies.

**Why the Correct Answer is Right:** Membranous Nephropathy (MN) is a specific cause of nephritic syndrome. It is characterized by the presence of immune complex deposition on the subepithelial side of the glomerular basement membrane, leading to the loss of foot processes on electron microscopy. This immune complex deposition results in a poor response to corticosteroid therapy, as mentioned in the question. MN typically results from an autoimmune process, often associated with certain antibodies (PLA2R or M2) against the podocyte membrane.

**Why Each Wrong Option is Incorrect:**

**A.** Minimal Change Disease (MCD): MCD is a different cause of nephrotic syndrome, characterized by minimal change in the glomerular filtration barrier, not membranous nephropathy. MCD responds well to corticosteroid therapy.

**B.** Nephrotoxic medications: Some nephrotoxic medications, like contrast agents or certain chemotherapeutic agents, can cause nephritic syndrome. However, the poor response to corticosteroid therapy is not a defining feature of these conditions.

**C.** Nephrosclerosis: Nephrosclerosis refers to a process of chronic kidney disease, typically caused by hypertension, diabetes, or other systemic diseases. It does not present as membranous nephropathy or have a poor response to corticosteroid therapy.

**D.** Membranous Nephropathy (MN): As explained earlier, MN is the correct answer, characterized by immune complex deposition on the subepithelial side of the glomerular basement membrane, leading to loss of foot processes on electron microscopy and poor response to corticosteroid therapy.

**Clinical Pearl:** Membranous Nephropathy is an important differential diagnosis for nephrotic syndrome in a patient with nephritic features and poor response to corticosteroid therapy. A correct diagnosis and management plan are crucial, as MN is a treatable cause of end-stage renal disease. In the context of the question, corticosteroid therapy is not effective in MN due to the described pathophysiology.