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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Needle-shaped negatively birefringent monosodium urate crystals
- Classic abrupt first MTP pain, erythema, swelling, often overnight
- Acute monoarthritis requires arthrocentesis when diagnosis or infection status is uncertain
- Acute flare treatment: NSAID, colchicine, or glucocorticoid depending on comorbidities
- Allopurinol is first-line chronic urate-lowering therapy; titrate to serum urate <6 mg/dL
Overview
Gout is an inflammatory arthritis caused by monosodium urate deposition due to urate overproduction, underexcretion, or both. Renal underexcretion is most common. Serum urate may be normal during an acute flare.
Epidemiology
Gout is common in men, postmenopausal women, CKD, metabolic syndrome, obesity, hypertension, heart failure, and diuretic use. Alcohol, high-fructose beverages, red meat, organ meats, and shellfish can trigger flares.
Clinical Features
Symptoms
Abrupt severe monoarticular pain peaking within 12-24 hours
Podagra with first MTP warmth, erythema, and swelling
Flares triggered by alcohol, dehydration, surgery, trauma, infection, or ULT initiation
Recurrent attacks involving ankles, knees, wrists, elbows, or fingers
Fever or systemic toxicity requires evaluation for septic arthritis
Severe tenderness to light touch or bedsheet contact
Signs
Hot swollen exquisitely tender joint with reduced ROM
Tophi on ears, olecranon bursae, fingers, toes, or Achilles tendon
Erosive deformity in chronic tophaceous gout
Skin desquamation as flare resolves
Prosthetic joint, immunosuppression, or persistent fever raises infection concern
Investigations
First-line
ArthrocentesisSynovial WBC, Gram stain, culture, and crystal analysis; gout crystals are needle-shaped and negatively birefringent
Serum uric acidCan be normal during acute flare; do not use alone to exclude gout
CBC, ESR, CRPMay be elevated but cannot distinguish gout from septic arthritis
Second-line
Renal function and liver testsGuide NSAID, colchicine, allopurinol, and febuxostat safety
Plain radiographsChronic gout shows punched-out erosions with overhanging edges
UltrasoundDouble-contour sign and tophi can support diagnosis
Specialist
Dual-energy CTDetects urate deposition in atypical or difficult-to-aspirate disease
1
Acute flare
- Treat promptly with NSAID, colchicine, or glucocorticoid
- Use NSAIDs only if kidney, GI, HF, anticoagulation, and CV risk allow
- Colchicine works best early and needs renal/drug-interaction adjustment
- Use oral or intra-articular glucocorticoids when NSAIDs/colchicine are unsuitable
2
Urate-lowering therapy
- Start ULT for tophi, radiographic damage, frequent flares, CKD stage >=3, serum urate >9, or uric acid stones
- Allopurinol is preferred first-line, including CKD; start low and titrate
- Treat-to-target serum urate <6 mg/dL
- Provide flare prophylaxis for at least 3-6 months when starting ULT
3
Key principles
- Do not stop allopurinol during an acute flare if already taking it
- Febuxostat is an alternative but consider cardiovascular risk
- Probenecid is less useful in CKD and avoided with uric acid stones
Complications
- Tophaceous gout: Soft-tissue urate deposits causing deformity and skin breakdown
- Erosive arthritis: Punched-out erosions with overhanging edges
- Kidney stones: Uric acid nephrolithiasis
- Diagnostic trap: Crystals do not exclude concurrent infection
USMLE Step 2 CK Exam Tips
- 1Needle-shaped negatively birefringent crystals = gout
- 2Serum uric acid can be normal during an acute attack
- 3Do not stop allopurinol during a flare
- 4Acute gout in CKD: avoid NSAIDs; use steroids or adjusted colchicine
- 5Recurrent gout + CKD or tophi = start allopurinol and titrate to urate <6
- 6Podagra after alcohol or seafood is classic
- 7Crystals do not rule out septic arthritis
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