Next Investigation for Sudden Onset Itching in the Right Eye with Potential Rheumatoid Arthritis or Gout
For a patient with sudden onset of itching in the right eye and potential rheumatoid arthritis or gout, the next investigation should be a comprehensive ophthalmologic examination including slit lamp examination and synovial fluid analysis from affected joints to establish definitive diagnoses. 1
Ophthalmologic Evaluation
Initial Eye Examination
- Complete slit lamp examination to assess for signs of conjunctivitis, uveitis, or other inflammatory eye conditions 1
- Evaluation of anterior chamber for cells and flare to rule out uveitis, which can be associated with rheumatoid arthritis 1
- Assessment for keratic precipitates, increased flare, or other signs of ocular inflammation 1
Specific Tests for Eye Symptoms
- Tear immunoglobulin E (IgE) quantification if allergic conjunctivitis is suspected 1
- Allergy skin testing which is highly sensitive and specific for aeroallergens if allergic etiology is suspected 1
- Conjunctival allergen challenge in cases where a specific allergen is suspected 1
Rheumatologic Evaluation
For Gout Diagnosis
- Synovial fluid aspiration and analysis from affected joints for monosodium urate (MSU) crystals, which is the gold standard for definitive diagnosis of gout 1, 2, 3
- Polarized light microscopy of synovial fluid to identify needle-shaped, negatively birefringent MSU crystals 2, 3
- Serum uric acid measurement, although not diagnostic alone, is essential for management 1, 2
For Rheumatoid Arthritis Evaluation
- If RA is suspected, appropriate serologic testing should be performed (rheumatoid factor, anti-CCP antibodies) 4, 5
- Consider imaging studies of affected joints to assess for erosive changes characteristic of RA 5
Diagnostic Algorithm
First step: Complete ophthalmologic examination including slit lamp examination to identify the cause of eye itching 1
- Look for signs of conjunctivitis, uveitis, or other inflammatory conditions
Second step: Synovial fluid aspiration and analysis from affected joints 1
- Essential for definitive diagnosis of gout through MSU crystal identification
- Should include Gram stain and culture to rule out infection, as gout and sepsis may coexist 2
Third step: Laboratory testing 1, 2
- Serum uric acid level (for gout management)
- Renal function tests (creatinine, BUN) for medication selection
- Complete blood count
- Inflammatory markers (ESR, CRP)
Fourth step: If synovial fluid analysis is not feasible or inconclusive, consider advanced imaging 1, 3
- Ultrasound scanning can detect tophi not evident on clinical examination or double contour sign at cartilage surfaces
- Dual-Energy CT (DECT) has high sensitivity (85-100%) and specificity (83-92%) for gout diagnosis
Special Considerations
- The coexistence of rheumatoid arthritis and gout, while previously thought to be rare, has been documented in multiple case reports and case series 4, 5, 6
- In patients with both conditions, standard treatment for one condition may not adequately address symptoms if both diseases are active 4
- Eye symptoms may be the presenting feature of systemic rheumatic disease and should not be overlooked 1
- For patients on hydroxychloroquine for rheumatoid arthritis who develop eye symptoms, consider ophthalmologic evaluation to rule out medication-related adverse effects 1
Pitfalls to Avoid
- Do not rely solely on serum uric acid levels for gout diagnosis, as levels may be normal during acute attacks 1, 2
- Do not assume that eye symptoms in a patient with rheumatic disease are always related to the rheumatic condition; common conditions like allergic conjunctivitis should still be considered 1
- Avoid diagnosing gout based on clinical features alone when synovial fluid analysis is feasible 1
- Do not overlook the possibility of coexistent conditions, as rheumatoid arthritis and gout can occur simultaneously despite traditional beliefs 4, 5, 7