Gout Progression
A gout diagnosis may be clear for patients with multiple acute attacks in a classic location such as the big toe. However, the variability of the course of the disease, and its similarities to other arthritic conditions, may make the diagnosis more challenging. Also, patients experiencing a gout flare may not have elevated serum urate levels during the attack.
A complete approach to diagnosis and treatment considers the natural history of gout in all of its four stages:
- Asymptomatic hyperuricemia
- Acute gout
- Intercritical (interval) gout—the periods between gout attacks
- Chronic tophaceous gout
Asymptomatic Hyperuricemia
Most patients with hyperuricemia will remain asymptomatic, and for those who do not, there is usually a delay of 20 years or more before the first episode of gouty arthritis or urolithiasis. (Between 10% and 40% of gout patients have at least one episode of renal colic before they have any joint symptoms). The likelihood of developing gout increases with increasing serum urate level.
Acute Gout
Gout usually develops in the first metatarsophalangeal joint and this first attack often occurs at night. During an acute attack, the affected joint becomes hot, red, swollen, and extremely tender. These symptoms may be accompanied by fever, particularly if more than one joint is involved. The attack may resolve in a few hours if very mild or it may last from days to weeks if severe.
In men, the first acute attack of gout usually occurs between the ages of 40 and 60. In women, the first attack is more common after age 60. For most patients, the initial attack comes on suddenly. Others have reported transient pain involving the ankles, heels, or big toe that preceded the attack.
In 85% to 90% of cases, a single joint is involved in the first attack. Gout primarily affects joints of the lower extremities but can affect any joint. A survey of 354 gout patients showed that 76% had experienced gout in their big toe, 50% in their ankle or foot, and 32% in their knee. However, 25% had experienced an attack in their finger, 10% in their elbow, 10% in their wrist, and 11% in more than one site simultaneously.
A definitive diagnosis can be made via aspiration of the joint and identification of intracellular needle-shaped urate crystals. A presumptive diagnosis of gout can often be made in the case of acute monoarticular arthritis that is accompanied by hyperuricemia and is responsive to anti-inflammatory therapy. However, sUA is not a good diagnostic tool during acute flares because levels may artificially lower due to effects of the inflammatory process itself. However, monitoring sUA in intercritical periods is key to understanding a patient's true medical history of hyperuricemia.
Intercritical or Interval Gout
In most gout patients, a second attack occurs within 6 months to 2 years of the first attack. The majority of patients will have a second gout attack within 1 year, and 78% will have a second attack within 2 years. Only 7% of patients have no recurrence after 10 or more years. As the disease progresses, the frequency of attacks usually increases in untreated patients.
Later attacks are more likely to involve multiple joints, start less explosively and then become more severe, are longer-lasting, and tend to resolve more gradually than initial attacks. Joint damage progresses and may continue even between flares. Clinical research suggests that monosodium urate crystals persist as long as hyperuricemia persists.
Advanced Tophaceous Gout
If hyperuricemia is left untreated, the interval between attacks may disappear, leaving patients with persistent low-grade joint inflammation, joint deformity, and tophaceous deposits of urate crystals. The discomfort of chronic gout may still include episodes of acute arthritis.
Tophi can occur at various locations, generally, but not always, within the same joint affected by acute gout. The tophi may not be painful, but periodic acute inflammation can occur around the site, causing intense pain. Extensive joint damage and the formation of very large tophi can lead to crippling deformities, particularly of the hands and feet, and chronic, constant pain.