Rheumatology Question 36 Instructor

What is a rheumatoid factor (RF)?

Rheumatoid factors are antibodies directed against the Fc region of IgG.

What percentage of patients with rheumatoid arthritis have a positive RF?

Only about 60% of patients with rheumatoid arthritis test positive for RF. The presence of a RF provides information about prognosis and disease severity, but not disease activity. Those with high titre RF are at greater risk for a severe disease course and for extra-articular manifestations.

List 4 other diseases that are associated with a positive RF.

Other conditions associated with a positive RF include:

  • Sjogren’s syndrome
  • scleroderma
  • polymyositis
  • dermatomyositis
  • mixed connective tissue disease
  • systemic lupus erythematosus
  • liver disease
  • lung fibrosis
  • HIV
  • endocarditis
  • syphilis
  • cryoglobulinemia
  • older age.

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