## **Core Concept**
The nephrotic syndrome is characterized by heavy proteinuria, hypoalbuminemia, hyperlipidemia, and edema. One of the complications of nephrotic syndrome is an increased risk of thrombosis, which is related to a hypercoagulable state. This hypercoagulable state is primarily driven by the loss of anticoagulant proteins in the urine and increased synthesis of clotting factors.

## **Why the Correct Answer is Right**
The correct answer, **C. Loss of Antithrombin III**, is right because antithrombin III (ATIII) is a key anticoagulant protein that inhibits thrombin and other clotting factors. In nephrotic syndrome, heavy proteinuria leads to the loss of ATIII in the urine, reducing its circulating levels. This decrease in ATIII activity tips the balance towards clotting, contributing to a hypercoagulable state. Additionally, the liver increases the production of clotting factors in response to hypoalbuminemia, further contributing to hypercoagulability.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Increased fibrinogen levels do contribute to a hypercoagulable state but are not the primary cause related to the nephrotic syndrome's pathophysiology. Fibrinogen levels can be elevated in nephrotic syndrome due to the increased hepatic synthesis of clotting factors in response to hypoalbuminemia, but this is not the most direct link.
- **Option B:** Decreased plasminogen levels can contribute to hypercoagulability because plasminogen is converted into plasmin, which is involved in fibrinolysis. However, the primary issue in nephrotic syndrome is the loss of anticoagulant proteins like ATIII.
- **Option D:** Increased albumin levels are not a feature of nephrotic syndrome; in fact, hypoalbuminemia is a hallmark. While albumin has some effects on fluid balance and can indirectly influence coagulation pathways, its decrease, not increase, is relevant.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that patients with nephrotic syndrome are at an increased risk of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE). This risk necessitates consideration of prophylactic anticoagulation in some cases, especially when the serum albumin level is very low.

## **Correct Answer:** C. Loss of Antithrombin III