Workup for Acute Gouty Attack
For acute gout, perform synovial fluid analysis with polarized light microscopy to identify monosodium urate (MSU) crystals when diagnostic testing is clinically indicated—this is the definitive diagnostic test. 1
Diagnostic Approach
Gold Standard Testing
- Synovial fluid aspiration with crystal analysis is the reference standard for diagnosing acute gout 1, 2
- MSU crystal identification permits definitive diagnosis 2
- Perform routine crystal search in all synovial fluid samples from undiagnosed inflamed joints 2
When Synovial Fluid Analysis Is Not Feasible
For typical presentations (recurrent podagra with hyperuricemia), clinical diagnosis alone is reasonably accurate but not definitive without crystal confirmation 2. The clinical picture to look for:
- Rapid symptom onset: Severe pain, swelling, and tenderness reaching maximum within 6-12 hours 2
- Overlying erythema highly suggestive of crystal inflammation 2
- Classic location: First metatarsophalangeal joint (podagra) most common
Laboratory Workup
Serum uric acid levels:
- Measure but recognize critical limitation: serum uric acid does NOT confirm or exclude gout 2
- Many with hyperuricemia never develop gout
- During acute attacks, serum levels may be normal 2
- Most important as a risk factor, not a diagnostic test 2
Additional testing when indicated:
- Gram stain and culture if septic arthritis suspected—gout and sepsis can coexist 2
- 24-hour urinary uric acid excretion for selected patients: family history of young-onset gout, onset under age 25, or renal calculi 2
Imaging Studies
Plain radiographs:
- NOT useful for confirming early or acute gout 2
- May help with differential diagnosis
- Show typical features only in chronic gout 2
Advanced imaging (ultrasound, dual-energy CT):
- Increasingly important diagnostic tools 3, 4
- Particularly useful when joint aspiration not feasible
- Can identify MSU deposits in asymptomatic joints during intercritical periods 2
Comorbidity Assessment
Evaluate cardiovascular and metabolic risk factors 2, 5:
- Obesity
- Hyperglycemia
- Hyperlipidemia
- Hypertension
- Renal function 5
These assessments are essential as gout patients typically have multiple cardio-metabolic-renal diseases that increase cardiovascular events and mortality 4.
Common Pitfalls
- Do not rely solely on serum uric acid to make or exclude the diagnosis—normal levels during acute attacks are common 2
- Do not skip cultures when infection is possible—crystal presence doesn't exclude septic arthritis 2
- Do not order plain radiographs expecting them to confirm acute gout—they're only useful for chronic disease 2