Gout: an update.

Arthritis caused by gout (i.e., gouty arthritis) accounts for millions of outpatient visits annually, and the prevalence is increasing. Gout is caused by monosodium urate crystal deposition in tissues leading to arthritis, soft tissue masses (i.e., tophi), nephrolithiasis, and urate nephropathy. The biologic precursor to gout is elevated serum uric acid levels (i.e., hyperuricemia). Asymptomatic hyperuricemia is common and usually does not progress to clinical gout. Acute gout most often presents as attacks of pain, erythema, and swelling of one or a few joints in the lower extremities. The diagnosis is confirmed if monosodium urate crystals are present in synovial fluid. First-line therapy for acute gout is nonsteroidal anti-inflammatory drugs or corticosteroids, depending on comorbidities; colchicine is second-line therapy. After the first gout attack, modifiable risk factors (e.g., high-purine diet, alcohol use, obesity, diuretic therapy) should be addressed. Urate-lowering therapy for gout is initiated after multiple attacks or after the development of tophi or urate nephrolithiasis. Allopurinol is the most common therapy for chronic gout. Uricosuric agents are alternative therapies in patients with preserved renal function and no history of nephrolithiasis. During urate-lowering therapy, the dose should be titrated upward until the serum uric acid level is less than 6 mg per dL (355 micromol per L). When initiating urate-lowering therapy, concurrent prophylactic therapy with low-dose colchicine for three to six months may reduce flare-ups.