Source / episode info

• **Episode:**110
• **Title:**Divine Intervention Episode 110 – ABIM/Medicine ITE/USMLE Step 3 Review Series 8 (Rheumatology 2)
• **Published:**2019-06-08
• Source:Episode page

One-liner

This episode reviews seronegative spondyloarthropathies (PsA, As, IBD-As, RA), the diagnostic criteria and management of Diffuse Idiopathic Skeletal Hyperostosis (DISH), and the pathophysiology, diagnosis, and treatment strategies for gout, emphasizing key HLA associations.

High-yield summary

• Seronegative Spondyloarthropathies: Characterized by enthesitis and axial involvement; the four core diseases are Psoriatic Arthritis, Ankylosing Spondylitis, IBD-associated arthritis, and Reactive Arthritis (formerly Reiter's syndrome).
• Gout Pathophysiology: Caused by monosodium urate crystals (needle-shaped, negatively birefringent) depositing in joints; most cases result from under-excretion of uric acid.
• Acute Gout Management: Initial treatment is empirical (NSAIDs, Corticosteroids, Colchicine); never measure serum uric acid levels during an acute flare.
• Chronic Gout Therapy: First-line agents are Xanthine Oxidase Inhibitors (Allopurinol, Febuxostat), aiming for a target uric acid level of < 6 mg/dL (or < 5 mg/dL if tophaceous).
• DISH vs. AS: DISH is characterized by ossification of the anterior longitudinal ligament and multiple bridging osteophytes, crucially lacking sacroiliac joint inflammation or sclerosis.
• HLA Associations: Remember HLA-B27 for seronegative SpA; check for HLA-B57:01 before Abacavir; be aware of HLA-B58:01 in Asians regarding Allopurinol risk.

Learning objectives

• Differentiate the clinical presentation and imaging findings among the four seronegative spondyloarthropathies (PsA, As, IBD-As, ReA).
• Master the acute vs. chronic management principles for gout, including appropriate drug selection and contraindications.
• Recognize the key features of Diffuse Idiopathic Skeletal Hyperostosis (DISH) versus inflammatory sacroiliitis.
• Understand the clinical significance of specific HLA alleles in rheumatology and anti-infective therapy.
• Apply knowledge of differential diagnosis for acute arthritis, distinguishing crystal deposition from septic or infectious causes.