DIP Episode 121 - USMLE Step 2CK Rapid Review Series 5 (IM/Peds)

Source / episode info

• Episode: 121
• Title: Divine Intervention Episode 121 – USMLE Step 2 CK Rapid Review Series 5 (IM/Peds)
• Published: 2019-07-17
• Source: Episode page

One-liner

This episode reviews high-yield topics including the workup of SBP (paracentesis), causes of eosinophilia (AIN/allergies/neoplasms), specific urinary casts and AKI patterns (rhabdomyolysis, nephrotic syndrome), classic vascular syndromes (AAA, LERICH), and complex pediatric immunodeficiency disorders.

High-yield summary

• SBP Workup: Suspect SBP in chronic alcoholics with fever, abdominal pain, and ascites; diagnosis requires paracentesis fluid analysis: WBC count >250 cells/mm³ or positive culture/Gram stain for gram-negative organisms. Treatment involves empiric antibiotics covering gram-negatives (e.g., ceftriaxone) and prophylactic fluoroquinolone.
• Eosinophilia Differential: The mnemonic DN quadruple ACP helps recall causes: Drugs, Neoplasms, Asthma, Allergies, Acute Interstitial Nephritis (AIN), Collagen Vascular Disease, Parasites. AIN is a classic cause associated with fever/rash/eosinophilia.
• Acute Abdominal Aortic Syndrome (AAA): Always consider AAA in smokers presenting with severe abdominal pain and low blood pressure; the "Draped Adyos sign" on imaging suggests contained or ruptured AAA due to posterior wall involvement over the vertebral body.
• Immunodeficiency Syndromes: Recognize specific patterns: B-cell defects (Bruton's -> recurrent bacterial infections, hypogammaglobulinemia); T-cell defects (DiGeorge -> recurrent viral/fungal infections, hypocalcemia due to absent parathyroid tissue).
• Urinary Casts & AKI: Rhabdomyolysis causes "positive for blood on dipstick, negative for RB Cs on microscopy." Hyaline casts are seen in dehydration and increased ADH activity. Red cell casts indicate glomerulonephritis.

Learning objectives

• Differentiate the clinical presentations of various immunodeficiency syndromes (B-cell vs T-cell defects).
• Identify high-yield associations for acute kidney injury based on urinary sediment and history (e.g., rhabdomyolysis, casts).
• Recognize atypical signs of vascular emergencies like AAA rupture.
• Apply knowledge of the differential diagnosis for eosinophilia using mnemonic devices.
• Understand the pathophysiology and clinical consequences of congenital endocrine/immunodeficiency syndromes (DiGeorge, Bruton's).

Board exam buzzwords

Rapid review table

Board-speak -> diagnosis

Differential diagnosis / distinguishing features

Acute Kidney Injury Causes

Immunodeficiency Syndromes

Management pearls

• SBP: Treat empirically with a third-generation cephalosporin (e.g., ceftriaxone) for 5–7 days, regardless of culture results initially.
• AAA: High suspicion in smokers presenting with severe abdominal pain and hypotension; imaging (CT scan) is mandatory if stable enough.
• Rhabdomyolysis: Aggressive IV fluid resuscitation (Mannitol or saline) to prevent acute tubular necrosis (ATN); monitor urine output and electrolytes closely.
• DiGeorge Syndrome: Management focuses on calcium supplementation and monitoring of parathyroid hormone (PTH) levels due to hypoparathyroidism.

Don't miss

Integration & clinical reasoning

• Vascular & Renal: Both AAA and severe rhabdomyolysis can lead to acute kidney injury (AKI) via renal hypoperfusion/ischemia, necessitating aggressive fluid management.
• Endocrine & Immune: DiGeorge syndrome links endocrine failure (hypoparathyroidism -> hypocalcemia) directly with immune deficiency (T-cell defect).
• Infectious Disease: SBP is a common complication of advanced liver disease (cirrhosis), linking GI/hepatic status to systemic infection risk.

OMM / COMLEX integration

• For any acute abdominal pain/bleeding scenario (e.g., suspected AAA rupture), standard emergency management takes priority: immediate stabilization (IV fluids, blood pressure support) and rapid imaging (CT angiography if stable). OMT is adjunctive only after hemodynamic stability is achieved.
• When managing severe AKI from rhabdomyolysis, aggressive fluid resuscitation is paramount to prevent tubular cast formation and ATN; this requires continuous monitoring of urine output and electrolytes.

Concept connections / cross-references

• For detailed review on the pathophysiology and management of cirrhosis complications, see [Episode 105].
• For comprehensive coverage of vasculitis and autoimmune disorders, see [Episode 88].
• For general principles of pediatric infectious disease workups, see [Episode 42].

High-yield association table

Key terms glossary

Study optimization

Question pattern recognition

• The "Red Flag" Syndrome: Recognizing a constellation of symptoms that point to a rare or severe diagnosis (e.g., AAA, SBP, immunodeficiency syndromes).
• Differential Diagnosis by Finding: Given a lab result (e.g., eosinophilia, low Ig) and requiring the most likely underlying cause.
• Connecting Systems Failure: Understanding how failure in one system (e.g., liver -> ascites/SBP; endocrine -> hypocalcemia/seizures) impacts others.

Test yourself

Common mistakes to avoid

Common traps