Rheumatoid Factor

Abbreviation: RF

Panel: Inflammation & Immune Markers · All inflammation tests

Typical adult reference range

Conventional units<14 IU/mL
SI units<14 IU/mL

Ranges vary between laboratories and methods — compare your result with the range printed on your own report.

What a high or low result can mean

High rheumatoid factor: positive results can be seen in rheumatoid arthritis, other autoimmune diseases, chronic infections, and some healthy older adults.

These are associations, not a diagnosis: the same result can have several causes, and your clinician interprets it with the rest of your results and history.

Good to know

Cut-offs vary between assays.

Please note: Reference ranges vary between laboratories, and between the methods and instruments they use — the range printed on your own report is the one your result should be compared with. A result outside the range is not by itself a diagnosis, and a result inside it does not rule out illness. These pages are an educational summary, not medical advice: always discuss your results with the clinician who ordered them, who can interpret them in the context of your health and history.