From the Guidelines
Gout is most accurately diagnosed by identifying monosodium urate crystals in joint fluid using polarized light microscopy, as recommended by the European League Against Rheumatism in 2020 1. This method is considered the gold standard for diagnosis. According to the American College of Physicians, synovial fluid analysis is recommended when clinical judgment indicates that diagnostic testing is necessary in patients with possible acute gout 1.
Diagnostic Approach
The diagnostic approach to gout involves a combination of:
- Clinical evaluation: considering the patient's medical history, physical examination, and risk factors such as diet, alcohol consumption, and family history
- Laboratory tests: including blood tests to measure uric acid levels, complete blood count, kidney function tests, and inflammatory markers
- Imaging studies: such as X-rays, ultrasound, or dual-energy CT scans to detect joint damage or urate crystal deposits
Importance of Clinical Judgment
Clinical judgment plays a crucial role in diagnosing gout, as the presence of hyperuricaemia alone is not sufficient for diagnosis 1. The European League Against Rheumatism recommends a three-step approach for the diagnosis of gout, which includes searching for MSU crystals, clinical diagnosis, and imaging 1.
Recent Guidelines
The 2020 European League Against Rheumatism guidelines emphasize the importance of synovial fluid aspiration and examination for crystals in patients with undiagnosed inflammatory arthritis 1. These guidelines also highlight that the diagnosis of gout should not be made on the presence of hyperuricaemia alone, as it has a low specificity for the diagnosis of gout 1.
Key Considerations
Key considerations in the diagnosis of gout include:
- The characteristic sudden onset of intense pain, swelling, and redness in joints, particularly the big toe
- The presence of monosodium urate crystals in joint fluid
- The patient's medical history and risk factors
- The results of laboratory tests and imaging studies By considering these factors and following the recommended diagnostic approach, healthcare providers can accurately diagnose gout and develop an effective treatment plan.
From the Research
Diagnosis of Gout
The diagnosis of gout can be made through various methods, including:
- Clinical presentation: Acute gouty arthritis typically presents with a sudden and severe exquisitely painful joint, most classically in the first metatarsophalangeal joint (toe) 2
- Laboratory findings: Demonstrating the presence of monosodium urate (MSU) crystals in the joint fluid or tophus has been the gold standard for the diagnosis of gout 2, 3
- Radiologic findings: Imaging modalities, including conventional radiography (CR), ultrasonography (US), magnetic resonance imaging (MRI), and dual-energy computed tomography (DECT), can provide information on the deposition of MSU crystals in tissues, and the consequences of such deposition 3
Diagnostic Tools
Some of the diagnostic tools used to diagnose gout include:
- Synovial fluid analysis: To demonstrate the presence of MSU crystals in aspirated joint fluid or tophus 2, 3
- Polarizing microscopy: To identify MSU crystals in synovial fluid, although agreement among medical and ancillary health personnel examining synovial fluid using polarizing microscopy appears to be poor 3
- Imaging modalities: Such as CR, US, MRI, and DECT, which can provide information on the deposition of MSU crystals in tissues, and the consequences of such deposition 3