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The Role of the Laboratory in the Diagnosis of Rheumatoid Arthritis

Utility of Rheumatoid Factor

Slide 8

August 2011

Rheumatoid factor is the classic marker used for the diagnosis of rheumatoid arthritis. Rheumatoid factor is an antibody, either an IgG, IgA, or IgM isotype, that recognizes the Fc portion of an IgG molecule. Most rheumatoid factor assays have reasonable sensitivity for rheumatoid arthritis, generally between 70 and 90%. However, the biggest problem with rheumatoid factor is a lack of specificity. It is found at relatively high frequencies in other connective tissue diseases. It can also be found in healthy individuals. The frequency of positivity for rheumatoid factor is age-related, and may approach 25% in individuals over 60 to 70 years of age. This lack of specificity led to investigations designed to find other diagnostic markers for rheumatoid arthritis.

Utility of Rheumatoid Factor


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