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Rheumatoid arthritis - Management
Investigations for synovitis
- Rheumatoid factor — is positive in 60–70% of people with rheumatoid arthritis (RA) but may also be positive in people with other inflammatory diseases and in those who are healthy. The presence or absence of rheumatoid factor does not exclude or confirm a diagnosis of RA.
- C-reactive protein or erythrocyte sedimentation rate — inflammatory markers are usually, but not always, elevated in RA.
- Full blood count — normochromic, normocytic anaemia and reactive thrombocytosis are common in active RA.
- Urea and electrolytes — most treatments for RA can affect renal function, therefore a baseline measure is useful prior to starting treatment.
- Liver function tests — mild elevations of alkaline phosphatase and gamma-glutamyltransferase are common in active RA.
- Antinuclear antibodies (ANA) — may suggest connective tissue diseases such as systemic lupus erythematosus (SLE). However, ANA is positive in up to 30% of people with RA who are also rheumatoid factor positive, and may be weakly positive in up to 10% of healthy people.
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