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Arthritis and Rheumatism

What Does a Negative Rheumatioid Factor Indicate?

10/22/2008

Question:

Can you tell me what it means when a blood test shows a rheumatoid factor of negative (<20iu/mi)?

Answer:

A Rheumatoid Factor (RF) blood test is typically checked to help with the diagnosis of Rheumatoid Arthritis as anywhere between 70% to 85% of people with Rheumatoid Arthritis will have an elevation in their RF level. A 'negative' RF simply refers to the fact that the RF was within normal limits (in your case, less than 20 IUs per ml).

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Response by:

Raymond  Hong, MD, MBA, FACR Raymond Hong, MD, MBA, FACR
Formerly, Assistant Professor of Medicine
School of Medicine
Case Western Reserve University