**Question:** Edema in nephrotic syndrome is mainly due to

A. Proteinuria
B. Oedema
C. Hypoalbuminemia
D. Increased capillary filtration

**Core Concept:** Nephrotic syndrome is a clinical condition characterized by severe proteinuria, hypoalbuminemia, hyperlipidemia, and edema. These features are typically associated with damage to the glomerular filtration barrier, leading to increased protein loss and fluid filtration into the interstitial space.

**Why the Correct Answer is Right:** Edema in nephrotic syndrome is primarily caused by hypoalbuminemia. Albumin is a plasma protein that plays a crucial role in maintaining oncotic pressure, which helps maintain the integrity of the interstitial fluid and prevents fluid leakage into the interstitial space. In nephrotic syndrome, due to hypoalbuminemia (low serum albumin levels), there is a decrease in oncotic pressure, leading to increased filtration of protein-free water and plasma proteins into the interstitial space, resulting in edema.

**Why Each Wrong Option is Incorrect:**

A. Proteinuria: Although proteinuria is a hallmark of nephrotic syndrome, it is not the primary cause of edema. Hypoalbuminemia plays a more significant role in causing edema.

B. Oedema: This is a vague term and does not address the underlying mechanism of edema in nephrotic syndrome.

C. Hypoalbuminemia: Although hypoalbuminemia is a consequence of nephrotic syndrome, it is not the primary cause of edema. The primary cause is the decrease in oncotic pressure due to hypoalbuminemia.

D. Increased capillary filtration: While increased capillary filtration can contribute to fluid leakage, it does not explain the primary cause of edema in nephrotic syndrome. The primary cause is the decrease in oncotic pressure resulting from hypoalbuminemia.

**Clinical Pearl:** Nephrotic syndrome patients often present with edema, which is primarily caused by hypoalbuminemia reducing oncotic pressure, leading to increased fluid filtration into the interstitial space. Treatment strategies focus on managing complications, such as hypoalbuminemia, hyperlipidemia, and infections, to prevent severe complications like pulmonary edema and liver dysfunction.