Source / episode info
- **Episode:**274
- **Title:**Divine Intervention Episode 274 – USMLE Step 2CK Rapid Review Series 45.
- **Published:**2020-11-28
- Source:Episode page
One-liner
This rapid review covers high-yield mechanisms including iron deficiency anemia from hookworm infection, B12 deficiency workup, transplant complications related to immunosuppressants (Cyclosporin, Mycophenolate), AML treatment with ATRA, the pathophysiology of pulmonary hypertension in scleroderma, and the three types of atelectasis.
High-yield summary
- Iron Deficiency Anemia: Chronic GI blood loss (e.g., hookworm/Necator) leads to low serum ferritin, elevated TIBC, and decreased transferrin saturation.
- B12 Deficiency: Causes megaloblastic anemia; labs show elevated homocysteine AND elevated methylmalonic acid (MMA).
- Immunosuppressant Toxicity: Cyclosporin causes nephrotoxicity (afferent arteriole constriction) and gingival hyperplasia; Cyclophosphamide requires Mesna prophylaxis for hemorrhagic cystitis.
- AML Treatment: Acute Myeloid Leukemia associated with the t(15;17) translocation is treated with All-trans retinoic acid (ATRA), which forces blast differentiation into non-dividing, terminal cells.
- Pulmonary Hypertension (PH): In Scleroderma, PAH results from vascular fibrosis in the pulmonary arteries (CREST); ILD leads to PH via lung parenchymal disease. Primary PAH is often idiopathic or linked to BMPR2 mutations.
- Atelectasis: The three mechanisms are Obstructive (bronchus blockage), Exudative/Passive (fluid between pleurae), and Compressive (mass effect).
Learning objectives
- Differentiate between iron deficiency anemia caused by chronic GI blood loss versus B12 deficiency based on lab findings.
- Identify classic signs and complications associated with major immunosuppressive drugs (Cyclosporin, Mycophenolate, Cyclophosphamide).
- Apply knowledge of the pathophysiology of pulmonary hypertension in connective tissue diseases vs. primary causes.
- Recognize the mechanism of action for All-trans retinoic acid (ATRA) in treating acute leukemias.
- Classify atelectasis based on its underlying physical or mechanical cause (Obstructive, Exudative, Compressive).