Gout
Rheumatology
Illness script · Rheumatology
Gout
Monosodium urate crystal deposition in joints causing recurrent episodes of severe acute inflammatory arthritis, typically monoarticular.
This illness script for Gout covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.
01
Predisposing factors
- Male sex; postmenopausal women approach equal risk
- Hyperuricemia (uric acid >6.8 mg/dL) — necessary but not sufficient
- Diuretics (thiazides, loop), low-dose aspirin, cyclosporine elevate urate
- High-purine diet (red meat, shellfish), alcohol (especially beer)
- Chronic kidney disease impairs urate excretion
- Obesity, metabolic syndrome, hypertension strongly associated
02
Presentation
- Podagra (1st MTP joint) in ~50% — classic first attack
- Abrupt onset, often nocturnal, peaks within 12–24 hours
- Exquisite tenderness — cannot tolerate bedsheet on joint
- Erythema, warmth, swelling; may desquamate during resolution
- Tophi on helix of ear, Achilles tendon, olecranon bursa in chronic disease
- Triggers: alcohol binge, dehydration, surgery, contrast dye, dietary excess
03
Pathophysiology
- Urate supersaturation → monosodium urate (MSU) crystal precipitation in synovial fluid
- MSU crystals phagocytosed by neutrophils → NLRP3 inflammasome activation → IL-1β release
- Massive neutrophil recruitment → acute synovitis with erythema, warmth, swelling
- Chronic tophaceous deposits form in cartilage, tendons, soft tissue over years
04
Diagnostics
- Synovial fluid analysis: gold standard — negatively birefringent needle-shaped MSU crystals under polarized light
- Serum uric acid: often NORMAL during acute attack (falsely reassuring)
- Joint aspiration also rules out septic arthritis — critical step
- X-ray: 'rat-bite' erosions with overhanging edges and sclerotic margins (chronic gout)
- Dual-energy CT: detects urate deposits non-invasively; useful when aspiration not feasible
05
Management
- Acute attack: NSAIDs (indomethacin) first-line if no contraindications
- Colchicine (within 24–36 hours) highly effective; avoid in severe renal impairment
- Corticosteroids (oral/intra-articular) if NSAIDs and colchicine contraindicated
- Urate-lowering therapy (ULT): allopurinol or febuxostat — start after acute flare resolves (or continue if already on)
- Target uric acid <6 mg/dL; always co-prescribe colchicine prophylaxis when initiating ULT to prevent flare
06
Clinical pivots
How to separate this script from the look-alikes that show up on exams and on the wards.
Septic Arthritis
Synovial fluid with MSU crystals argues for gout, but high WBC (>50,000) and positive Gram stain/culture confirm septic arthritis — both can coexist
Pseudogout (CPPD)
Calcium pyrophosphate crystals are positively birefringent and rhomboid-shaped; affects knee/wrist more than 1st MTP
Cellulitis
Cellulitis lacks joint swelling/effusion and synovial fluid crystals; skin infection spreads diffusely without joint line tenderness
Reactive Arthritis
Reactive arthritis follows GI/GU infection, is oligoarticular, and lacks hyperuricemia or crystals on aspiration
Keep reading
Full library- Giant Cell ArteritisLarge-vessel granulomatous vasculitis of the aorta and its branches, classically affecting the temporal artery in patients >50.
- Greater Trochanteric Pain SyndromeLateral hip pain arising from gluteal tendinopathy and/or trochanteric bursitis at the greater trochanter, formerly called trochanteric bursitis.
Educational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.