Source / episode info
- **Episode:**370
- **Title:**Divine Intervention Episode 370 – USMLE Step 2CK/3 Rapid Review Series 71
- **Published:**2022-02-11
- Source:Episode page
One-liner
This episode provides a rapid review of high-yield topics including biostatistical test interpretation (sensitivity/specificity), the differentiation between primary and secondary adrenal insufficiency, management of C. difficile colitis, diagnosis of FSGS in IV drug users, recognition of Rocky Mountain spotted fever, and understanding vascular causes of chronic mesenteric ischemia.
High-yield summary
- Adrenal Insufficiency: Secondary AI (pituitary failure) preserves aldosterone because the zona glomerulosa is regulated by the Renin-Angiotensin-Aldosterone System (RAAS), not ACTH. Primary AI (adrenal destruction) leads to low cortisol AND low aldosterone/hyperkalemia.
- FSGS: The most common cause of nephrotic syndrome in IV drug users, African Americans, Hispanics, and obese individuals; characterized by heavy proteinuria (>3.5 g/day).
- C. difficile Colitis: Diagnosis requires detecting the toxin (not just the organism) in stool; treatment involves oral vancomycin or fidaxomicin for severe cases, as IV administration is suboptimal.
- Rocky Mountain Spotted Fever (RMSF): Caused by Rickettsia rickettsii; transmitted via ticks; treat empirically with doxycycline, regardless of age/pregnancy status. Rash classically starts on palms and soles.
- Chronic Mesenteric Ischemia: Pain out of proportion to physical exam findings, triggered by eating due to severe atherosclerosis in the superior or inferior mesenteric arteries (SMA/IMA).
- Paget's Disease of Bone: A metabolic bone disease diagnosed via a bone scan (nucleomedicine test); treated with bisphosphonates.
Learning objectives
- Differentiate the hormonal axes governing adrenal cortex function in primary versus secondary insufficiency.
- Interpret biostatistical measures (sensitivity, specificity, PPV, NPV) when diagnostic criteria are altered.
- Recognize the classic clinical triad of Paget's disease: bone pain/bone scan findings, elevated ALP, and potential osteosclerosis risk.
- Identify key populations at high risk for FSGS development.
- Master the diagnosis and management principles for C. difficile colitis, including appropriate antibiotic choice (oral vs IV).