Source / episode info

• **Episode:**390
• **Title:**Divine Intervention Episode 390 – USMLE Step 2CK/3 Rapid Review Series 74
• **Published:**2022-05-16
• Source:Episode page

One-liner

This rapid review emphasizes high-yield board topics including sarcoidosis manifestations (lupus perniobil, hypercalcemia), carcinoid syndrome pathophysiology (BFDR mnemonic, 5-HIAA), and critical pre-treatment monitoring protocols for immunosuppressants and chemotherapies.

High-yield summary

• Sarcoidosis: Classically affects women; key dermatologic findings include lupus perniobil and erythema nodosum. The disease can cause restrictive lung disease, granulomas in the heart's conduction system (risk of heart block), and hypercalcemia due to macrophage expression of 1--hydroxylase.
• Carcinoid Syndrome: Caused by metastatic neuroendocrine tumors (most commonly originating in the appendix/GI tract) that release excessive serotonin. Classic symptoms are remembered by the mnemonic BFDR: Bronchospasm, Flushing, Diarrhea, and Right-sided heart disease (e.g., tricuspid regurgitation).
• Serotonin Metabolism: The primary breakdown product of serotonin is measured as 5-HIAA (5-hydroxyindoleacetic acid); elevated levels suggest carcinoid syndrome. Low 5-HIAA in CSF can be seen in depression/suicidal ideation.
• Pulmonary Physiology: Reduced DLCO (diffusion capacity) in fibrotic lung disease (e.g., sarcoidosis, emphysema) is due to increased diffusion distance or decreased surface area for gas exchange.
• Drug Monitoring Rule: Before initiating immunosuppressants (e.g., cyclosporine) or chemotherapies (e.g., doxorubicin), always check: PFTs (Pulmonary Function Tests), LFTs (Liver Function Tests), TFTs (Thyroid Function Tests), and perform an ECG.
• Sarcoidosis Treatment: Corticosteroids are the primary treatment for sarcoidosis.

Learning objectives

• Recognize the classic triad and systemic manifestations of sarcoidosis, including specific dermatologic findings like lupus perniobil.
• Understand the pathophysiology and clinical presentation of carcinoid syndrome using the BFDR mnemonic.
• Identify critical baseline laboratory tests (PFTs, LFTs, TFTs) required before initiating immunosuppressive or chemotherapeutic agents.
• Explain the mechanism by which sarcoidosis causes hypercalcemia via macrophage enzyme activity.
• Differentiate between the clinical presentation of carcinoid syndrome and other GI/cardiac issues.