**Question:** Causes of Deep venous thrombosis include all of the following, Except.

A. Infection
B. Angiotensin II
C. Chronic kidney disease
D. Prolonged immobilization

**Core Concept:** Deep venous thrombosis (DVT) is a medical condition characterized by blood clot formation in the deep veins, most commonly in the legs. The clot can lead to potential complications such as pulmonary embolism (PE) and post-thrombotic syndrome. Understanding its causes is crucial for appropriate diagnosis and management.

**Why the Correct Answer is Right:** Angiotensin II is a hormone primarily involved in regulating blood pressure and volume balance in the body. It acts through angiotensin II receptors (AT1 and AT2) and is unrelated to blood clot formation or venous stasis.

**Why Each Wrong Option is Incorrect:**

1. Infection: While infections can cause inflammation and increased venous stasis, they are not directly responsible for blood clot formation in deep veins.
2. Chronic kidney disease: While kidney function is essential for coagulation regulation, chronic kidney disease itself is not a direct cause of DVT unless associated with other risk factors.
3. Prolonged immobilization: This is a significant risk factor for DVT, as it leads to venous stasis and reduced blood flow, promoting clot formation in the deep veins.

**Clinical Pearl:** Prolonged immobilization and other risk factors should be identified and managed to prevent DVT development. Early mobilization, compression stockings, and low-dose anticoagulation may be considered for high-risk patients. Infection and kidney disease need proper management for coagulation balance, but their direct involvement in DVT formation is limited.

**Correct Answer:** B. Angiotensin II