From the Guidelines
To diagnose gout, the most definitive method is to perform a synovial fluid analysis to look for monosodium urate (MSU) crystals, as recommended by the European League Against Rheumatism in 2020 1. This approach allows for a definitive diagnosis of gout, which is essential for initiating proper treatment and preventing joint damage and complications from chronic gout. Some key points to consider in the diagnosis of gout include:
- The presence of MSU crystals in synovial fluid or tophus aspirates is the gold standard for diagnosis, with a level of evidence of 2b and a grade of recommendation of B 1.
- Clinical features such as monoarticular involvement of a foot or ankle joint, previous similar acute arthritis episodes, rapid onset of severe pain and swelling, erythema, male gender, and associated cardiovascular diseases and hyperuricaemia can support a clinical diagnosis of gout when synovial fluid analysis is not feasible, with a level of evidence of 2b and a grade of recommendation of B 1.
- Imaging tests like ultrasound scanning can be helpful in establishing a diagnosis in patients with suspected gout flare or chronic gouty arthritis by detection of tophi or a double contour sign at cartilage surfaces, with a level of evidence of 1b and a grade of recommendation of A 1.
- Risk factors for chronic hyperuricaemia, such as chronic kidney disease, overweight, medications, and consumption of excess alcohol, should be searched for in every person with gout, with a level of evidence of 1a and a grade of recommendation of A 1.
- Systematic assessment for the presence of associated comorbidities, including obesity, renal impairment, hypertension, ischaemic heart disease, heart failure, diabetes, and dyslipidaemia, is recommended, with a level of evidence of 1a and a grade of recommendation of A 1. It is also important to note that the diagnosis of gout should not be made on the presence of hyperuricaemia alone, as recommended by the European League Against Rheumatism in 2020 1, and that blood tests measuring uric acid levels are helpful but not conclusive alone, as some people with high uric acid don't develop gout, while others with normal levels can have attacks. In terms of the quality of the evidence, the 2020 European League Against Rheumatism recommendations are based on a systematic review of the literature and have a high level of evidence, with most recommendations having a level of evidence of 1a or 1b, and a grade of recommendation of A or B 1. Overall, the diagnosis of gout requires a comprehensive approach that includes clinical evaluation, laboratory tests, and imaging studies, and the most definitive method is to perform a synovial fluid analysis to look for MSU crystals, as recommended by the European League Against Rheumatism in 2020 1.
From the Research
Diagnosis of Gout
To diagnose gout, the following methods can be used:
- Clinical criteria from the American College of Rheumatology 2
- Identification of monosodium urate crystals in synovial fluid of the affected joint 2, 3
- Clinical prediction rules 4
- Arthrocentesis and synovial fluid or tophus analysis if the diagnosis is uncertain 4
Clinical Presentation
Gout is characterized by:
- Painful joint inflammation, most commonly in the first metatarsophalangeal joint 2, 3
- Swelling, pain, or tenderness in a peripheral joint or bursa, including the development of a tophus 4
- Sudden and severe painful joint, most classically in the first metatarsophalangeal joint (toe) 3
Laboratory and Radiologic Findings
Laboratory and radiologic studies can help make the diagnosis of gout, including:
- Demonstrating the presence of monosodium urate (MSU) crystals in the joint fluid or tophus 3
- Synovial fluid analysis 2, 3
- Radiologic studies to evaluate joint damage 4
Risk Factors
Risk factors for gout include:
- Male sex 4
- Obesity 4
- Hypertension 4
- Alcohol intake 4
- Diuretic use 4
- A diet rich in meat and seafood 4
- Chronic kidney disease 4
- A diet heavy in fructose-rich food and beverages 4
- Being a member of certain ethnic groups, including Taiwanese, Pacific Islander, and New Zealand Maori 4
- Living in high-income countries 4