Source / episode info
- **Episode:**344
- **Title:**Divine Intervention Episode 344 – USMLE Step 2CK/3 Rapid Review Series 65 (+10/4-8 2CK/3 Course Reminder).
- **Published:**2021-10-03
- Source:Episode page
One-liner
This episode provides a rapid review of high-yield topics including the sequelae of Group A Strep infections (Erysipelas), differentiating IgAN from PIGN based on timing, recognizing diverse causes of Thrombotic Microangiopathy (TMA), and distinguishing between pseudogout and gout based on crystal morphology.
High-yield summary
- Erysipelas Sequelae: Following a Group A Strep skin infection (e.g., Erysipelas), the most likely potential sequela is Post-infectious Glomerulonephritis (PIGN); Rheumatic fever cannot occur after a strep skin infection.
- Nephritic Syndrome Timing: If hematuria occurs 1–6 days after an upper respiratory infection, suspect IgA Nephropathy (IgAN). If it occurs > 1 week later, suspect PIGN. Both are nephritic syndromes (< 3.5 g/day proteinuria).
- TMA Pathophysiology: TMA is characterized by microthrombi formation due to endothelial damage and platelet activation; causes include malignant hypertension, SLE flare, DIC, HUS, and TTP.
- Pseudogout vs. Gout: Pseudogout involves the deposition of calcium pyrophosphate dihydrate (CPPD) crystals, which are typically rhomboid-shaped and positively bi-refringent. Gout involves monosodium urate (MSU) crystals, which are needle-shaped and negatively bi-refringent.
- FSGS in HIV: In HIV patients with nephrotic syndrome due to FSGS (especially the collapsing variant), protein loss includes antithrombin III, leading to a hypercoagulable state and increased risk of PE/DVT.
Learning objectives
- Differentiate between IgA Nephropathy and Post-infectious Glomerulonephritis based on the timing of hematuria post-URI.
- Identify the specific crystal morphology (rhomboid vs. needle) and birefringence pattern for pseudogout versus gout.
- Recognize the risk factors and underlying pathophysiology leading to a hypercoagulable state in nephrotic syndrome, particularly FSGS in HIV.
- Classify different causes of Thrombotic Microangiopathy (TMA), including those related to hypertension or complement deficiencies.
- Interpret classic histological findings on kidney biopsies, such as thyroidization of the kidneys.
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