What is the recommended workup and management for a gout diagnosis?

Gout Diagnosis Workup

The definitive diagnosis of gout requires synovial fluid analysis with demonstration of monosodium urate (MSU) crystals, which should be performed in any patient with undiagnosed inflammatory arthritis when clinically feasible. 1

Diagnostic Approach: Three-Step Process

Step 1: Synovial Fluid Analysis (Gold Standard)

• Aspirate joint fluid from affected joint during acute attack
• Examine for MSU crystals using polarized light microscopy
• Look for needle-shaped, negatively birefringent crystals
• This is the most definitive diagnostic test with extremely high specificity (LR = 567) 1

Step 2: Clinical Diagnosis (When Crystal Analysis Not Feasible)

When synovial fluid analysis cannot be performed, clinical features supporting gout diagnosis include:

• Monoarticular involvement of first metatarsophalangeal joint (podagra) or ankle joint (highest diagnostic value, LR = 30.64) 1
• Previous similar acute arthritis episodes
• Rapid onset of severe pain and swelling (reaching maximum in <24 hours)
• Erythema over the affected joint
• Male gender
• Associated cardiovascular diseases
• Hyperuricemia 1

Step 3: Imaging (When Diagnosis Remains Uncertain)

• Ultrasound: Look for:
  • Double contour sign (highly specific for urate deposits)
  • Tophi not evident on clinical examination 1
• Dual-energy CT (DECT): Can identify MSU crystal deposits
• Plain radiographs: Limited value for acute gout diagnosis but may show:
  • Asymmetrical swelling (LR = 4.13)
  • Subcortical cysts without erosion (LR = 6.39) in chronic gout 1

Important Clinical Considerations

Hyperuricemia Assessment

• Hyperuricemia alone is insufficient for gout diagnosis 1
• However, it is a major risk factor (LR = 9.74) 1
• Approximately 10% of gout patients may have normal serum uric acid during acute attacks 1

Risk Factor Evaluation

All gout patients should be systematically assessed for:

1. Risk factors for chronic hyperuricemia:

   • Chronic kidney disease
   • Overweight/obesity
   • Medications (diuretics, low-dose aspirin, cyclosporine, tacrolimus)
   • Excess alcohol consumption (particularly beer and spirits)
   • Non-diet sodas
   • High purine diet (meat and shellfish) 1

2. Associated comorbidities:

   • Hypertension
   • Ischemic heart disease
   • Heart failure
   • Diabetes
   • Dyslipidemia
   • Obesity
   • Renal impairment 1

Common Pitfalls to Avoid

1. Relying solely on serum uric acid levels - Hyperuricemia alone is insufficient for diagnosis, and some patients may have normal levels during acute attacks 1

2. Missing septic arthritis - Always consider joint infection in the differential diagnosis, especially with monoarticular presentation

3. Inadequate joint aspiration technique - Improper handling or delayed analysis can lead to crystal dissolution and false-negative results

4. Overlooking comorbidities - Systematic assessment for cardiovascular and metabolic conditions is essential 1

5. Premature initiation of urate-lowering therapy - This should be started after resolution of the acute attack to prevent flare exacerbation 2

The EULAR guidelines provide the most comprehensive and evidence-based approach to gout diagnosis, emphasizing the importance of crystal identification when possible, but acknowledging the practical reality that clinical diagnosis based on characteristic features may be necessary in many primary care settings 1.