What laboratory tests and treatments are used to manage gout?

Laboratory Tests and Treatments for Gout Management

The definitive diagnosis of gout requires identification of monosodium urate crystals in synovial fluid or tophus aspirate, with serum uric acid measurement being essential for ongoing management and monitoring of treatment efficacy. 1, 2

Diagnostic Laboratory Tests

• Synovial fluid analysis through polarized light microscopy is the gold standard for definitive diagnosis of gout, revealing needle-shaped, negatively birefringent crystals 2
• Serum uric acid (SUA) level should be measured in all patients, though hyperuricemia alone is insufficient for diagnosis as many patients with hyperuricemia never develop gout, and some patients with acute gout may have normal SUA levels during an attack 2
• Renal function tests (creatinine, BUN) are essential for medication selection and dosing, especially for urate-lowering therapy 2
• Screening for uric acid overproduction (by urine uric acid evaluation) is recommended in patients with gout onset before age 25 or history of urolithiasis 3
• Assessment of cardiovascular risk factors is recommended in all gout patients 1, 4

Management of Acute Gout Attacks

• First-line options for acute gout attack treatment include:

  • Low-dose colchicine (0.6 mg once or twice daily) with dose adjustment for renal impairment 5
  • NSAIDs with proton pump inhibitor protection 1
  • Glucocorticoids (oral, intraarticular, or intramuscular) 3

• For colchicine treatment:

  • Monitor for adverse effects including gastrointestinal symptoms and bone marrow depression 5
  • Adjust dosing in patients with renal impairment - for severe impairment, treatment course should not be repeated more than once every two weeks 5
  • Be aware of drug interactions, particularly with CYP3A4 inhibitors like clarithromycin, ketoconazole, and ritonavir 5

Long-term Management with Urate-Lowering Therapy (ULT)

• Indications for ULT include:

  • Tophaceous gout
  • Radiographic damage due to gout
  • Frequent gout flares (two or more per year)
  • Chronic kidney disease
  • Urolithiasis 3, 6

• Allopurinol is the preferred first-line ULT, even for patients with moderate-to-severe chronic kidney disease 3

  • Start at low dose (≤100 mg/day, lower in chronic kidney disease) 3, 7
  • Titrate dose gradually based on serum urate levels and renal function 7
  • Monitor liver function tests, BUN, and serum creatinine or creatinine clearance periodically 7

• The target serum urate level is <6 mg/dL for most patients and <5 mg/dL for those with severe gout (tophi, frequent attacks) 3, 8

• Regular monitoring of serum urate levels is essential to guide ULT dose titration 1, 9

Prophylaxis During ULT Initiation

• When initiating ULT, concomitant anti-inflammatory prophylaxis therapy for at least 3–6 months is strongly recommended to prevent flares 3
• Options for prophylaxis include:
  • Low-dose colchicine (0.6 mg once or twice daily) 1, 10
  • Low-dose NSAIDs with gastroprotection 10

Non-Pharmacological Management

• Dietary recommendations include:
  • Limiting alcohol intake, especially beer and spirits 4
  • Avoiding sugar-sweetened drinks and foods rich in fructose 4
  • Limiting intake of purine-rich foods (red meat, seafood) 4
  • Encouraging consumption of low-fat dairy products 4
  • Weight loss if overweight or obese 4

Common Pitfalls to Avoid

• Relying solely on serum uric acid for diagnosis, as SUA may be normal during acute attacks 2
• Failing to perform synovial fluid analysis when possible, which can lead to misdiagnosis 2
• Not providing prophylaxis when initiating ULT, which can lead to increased flares 3, 1
• Inadequate dosing of ULT and not titrating to reach target serum urate levels 1, 9
• Not considering drug interactions, particularly with colchicine and allopurinol 7, 5
• Not addressing modifiable lifestyle factors and comorbidities 1, 4
• Not monitoring renal function when using allopurinol, which requires dose adjustment in renal impairment 7

Special Considerations

• For patients with renal impairment:

  • Adjust allopurinol dosing based on creatinine clearance 7
  • For colchicine, reduce dosing frequency in severe renal impairment 5
  • Consider monitoring for oxipurinol accumulation in patients with decreased renal function 9

• For elderly patients:

  • Use caution with colchicine due to decreased renal function, concomitant disease, or other drug therapy 5
  • Dose selection should be cautious, starting at the lower end of the dosing range 5