Recognizing And Treating Lower Extremity Gout
- Volume 25 - Issue 2 - February 2012
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What Are The Reliable Diagnostic Indicators Of Gout?
Obtaining a comprehensive patient history, comorbidities, concomitant medication use, physical exam and family history is absolutely critical for the optimum treatment and management of gout.5 Janssens and colleagues generated a diagnostic scoring system that can be helpful in detecting gout.6 The variables in their system included male sex, previous patient arthritis attack, onset within one day, joint redness, MPJ involvement and serum uric acid level exceeding 5.8 mg/dL. Additional variables are hypertension or one or more cardiovascular diseases (angina pectoris, myocardial infarction, heart failure, cerebrovascular accident, transient ischemic attack, vascular disease), hospitalization, surgery and diuretic use.
The system by Janssens and colleagues was based on a scale of 0-13.6 From a diagnostic view, a score of 4 or less ruled out gout in 100 percent of patients. For patients with a score of 8 or higher, the diagnosis of gout was confirmed in more than 80 percent of these patients. One must also consider other diagnoses such as rheumatoid arthritis, sepsis, pseudogout, psoriatic arthritis and reactive arthritis in the patient’s initial presentation.
It is well noted that the identification of monosodium urate crystals in joint fluid and tophi is considered a gold standard for the diagnosis of gout.7 The majority of outpatient podiatry practices do not routinely practice the identification of crystals, according to a recent survey, and that is true in my practice as well.8 For example, in one study, the search for crystals only occurred in 11 percent of the patients with gout.9 Identifying crystals is more common in the offices of a rheumatologist, orthopedist or medical internist.
When identified, monosodium urate crystals appear to be needle-shaped and 2 to 20 μm in length. Under polarized light, they exhibit strong negative birefringence. The crystals appear yellow with a line parallel to the slow vibration of the compensator and appear blue when the line is perpendicular to it. If one suspects a sepsis process, the synovial fluid analysis is absolutely essential. Measuring the increased uric acid levels may be unreliable for diagnosis and can be misleading in either direction.
Serum urate levels may aid in supporting the diagnosis of gout. However, be aware that serum urate levels can be misleading in some cases and unreliable for the diagnosis of gout. For example, a patient with joint pain with elevating serum urate may be inappropriately diagnosed with gout. Someone with a truly gouty attack who has normal serum urate levels may not actually have gout. Laboratory testing is only part of making a diagnosis. One may consider X-rays, ultrasound or magnetic resonance imaging (MRI). More recently, researchers noted that a new therapeutic imaging technique — dual-energy computed tomography (CT) — can identify four times as many areas of involvement than the standard clinical assessment. It may actually replace the gold standard of joint aspiration.10