Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.

Rheumatoid factor (RF)

Rheumatoid factor (RF) is a protein (antibody) made by the immune system that can attack the body's own tissues. An elevated rheumatoid factor may mean the presence of an inflammatory disease.

Rheumatoid factor can be measured with a blood test. This is most helpful for diagnosing rheumatoid arthritis, lupus, and Sjögren's syndrome. Certain heart and liver diseases, infectious diseases (such as tuberculosis), and normal aging may also increase RF levels.

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Travel Warnings and Tips for Pregnant Women

If you decide to vacation, visit old friends, or must travel for work, pregnancy shouldn’t stop you from flying or