It is important to realise that the presence or absence of rheumatoid factor is of prognostic and NOT diagnostic value.
The differential diagnosis or early RA includes:
- viral arthritis (e.g. parvovirus, rubella, hepatitis B)
- reactive arthritis (e.g. post-infection: throat, gut, sexually acquired)
- seronegative spondyloarthropathy (e.g. psoriatic, ankylosing spondylitis, Reiter's disease, inflammatory bowel disease)
- connective tissue disease (e.g. systemic lupus erythematosus, scleroderma)
- polymyalgia rheumatica
- polyarticular gout
- septic arthritis
- medical conditions presenting with arthropathy (e.g. sarcoidosis, thyroid disease, infective endocarditis, haemochromatosis, diabetic cheiroarthropathy, paraneoplastic syndromes, multiple myeloma)
- Lyme disease
- MeReC Bulletin 2007;17(5):1-8.