Source / episode info

• **Episode:**612
• **Title:**DIP Ep 612: USMLE Step 2/3 Rapid Review Series 125
• **Published:**2025-06-25
• Source:Episode page

One-liner

This rapid review series emphasizes the pathophysiology of venous thromboembolism via Virchow's triad components, common causes of electrolyte abnormalities like hyponatremia (SSRIs, Oxytocin), and high-yield associations in endocrinology/gynecology (OCP risks, PCOS management).

High-yield summary

• Virchow's Triad: Thrombosis results from the combination of Stasis (e.g., immobility, heart failure), Hypercoagulability (e.g., OCPs, malignancy, Factor V Leiden), and Endothelial Dysfunction (e.g., vascular surgery, central lines).
• Alcoholic Liver Disease Labs: Elevated GGT is common because alcohol is a mitochondrial poison; the AST:ALT ratio is typically greater than 1:1 (though the specific >2:1 rule is often unreliable on exams).
• Hyponatremia Causes: The most common drug cause of SIADH-related hyponatremia is SSRIs. In obstetrics, prolonged oxytocin infusion can cause ADH release and subsequent dilutional hyponatremia.
• OCP Use in Gynecology: OCPs are primary treatments for acne (in reproductive age females), PCOS, endometriosis, and adenomyosis, but estrogen-containing COCs significantly increase the risk of venous thromboembolism (VTE).
• PE Workup Principle: In a patient with CHF exacerbation or prolonged immobility, always consider PE/DVT due to increased blood stasis and hypercoagulability. Imaging should be CT chest angiogram with IV contrast.
• PNH Pathophysiology: Paroxysmal nocturnal hemoglobinuria (PNH) causes thrombosis not just because of the gene mutation, but because the resulting complement overactivation leads to chronic inflammation and a prothrombotic state.

Learning objectives

• Identify the three components of Virchow's triad and list common clinical causes for each component.
• Differentiate between various causes of hyponatremia (e.g., SSRIs vs. Oxytocin vs. SIADH).
• Select appropriate hormonal management strategies (OCPs) for reproductive-age females with acne, PCOS, or endometriosis.
• Interpret liver function tests in the context of alcoholism (GGT elevation and AST:ALT ratio).
• Recognize that prolonged immobility/heart failure exacerbation significantly increases PE risk due to stasis.