Most common cause of nephrotic range proteinuria in an adult is –
**Core Concept**
Nephrotic range proteinuria in adults is characterized by excessive loss of proteins (including albumin) in the urine, exceeding 3.5 grams per 1.73 square meters of body surface area per day. This condition is often associated with kidney damage and can be caused by various underlying diseases affecting the kidney glomeruli.
**Why the Correct Answer is Right**
The most common cause of nephrotic range proteinuria in adults is minimal change disease (MCD), a condition characterized by damage to the glomerular filtration barrier. In MCD, the foot processes of the podocytes are effaced, leading to increased permeability of the glomerular basement membrane. This results in the loss of large amounts of albumin and other proteins in the urine. The exact pathogenesis of MCD is not fully understood, but it is thought to involve immune-mediated damage to the glomeruli.
**Why Each Wrong Option is Incorrect**
**Option A:** Focal Segmental Glomerulosclerosis (FSGS) is another cause of nephrotic range proteinuria, but it is less common than MCD. FSGS is characterized by scarring of the glomeruli, leading to impaired filtration function.
**Option B:** Membranous nephropathy is a cause of nephrotic range proteinuria, but it is less common than MCD. Membranous nephropathy is characterized by thickening of the glomerular basement membrane due to immune complex deposition.
**Option C:** Diabetic nephropathy can cause nephrotic range proteinuria, but it is typically associated with a background of diabetes mellitus. Diabetic nephropathy is characterized by glomerular hypertrophy and basement membrane thickening.
**Clinical Pearl / High-Yield Fact**
Nephrotic range proteinuria is often associated with hyperlipidemia, thrombocytosis, and hypoalbuminemia. It is essential to screen patients with nephrotic range proteinuria for these complications and manage them appropriately.
**Correct Answer: C. Diabetic nephropathy is not the most common cause of nephrotic range proteinuria, but rather **Minimal Change Disease (MCD)**