Insight into your rheumatoid factor.
Rheumatoid factor is an antibody the immune system can produce against the body's own protein. The test is used for questions about joint complaints and is emphatically one piece of the puzzle, not a diagnosis in itself.
Also known as: RF, rheumatoid factor, rheuma factor
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Background
What is rheumatoid factor?
Rheumatoid factor (RF) is an antibody directed against one of the body's own proteins, namely the tail section of other antibodies. The test measures whether that rheumatoid factor is detectable in your blood and, if so, in what quantity. RF is one of the oldest and most widely used laboratory determinations for questions about inflamed joints.
An important nuance belongs with its interpretation. A detectable rheumatoid factor occurs in part of the people with rheumatoid arthritis, but also in people without joint disease, more often as age increases, and in other conditions such as long-lasting infections, liver conditions and Sjögren's syndrome. Conversely, part of the people with rheumatoid arthritis have no detectable rheumatoid factor. The result can therefore only be interpreted together with your complaints, physical examination and additional tests, and the diagnosis belongs in the consulting room.
In brief
Antibody
Directed against a body-own part of other antibodies
One piece
Gains meaning alongside complaints and examination
Not proof
Also occurs without joint disease
Not exclusion
A negative result does not rule out rheumatoid arthritis
Common reasons to test
When can insight into your Rheumatoid factor be valuable?
Below are some situations in which measuring Rheumatoid factor can provide insight.
Insight into your rheumatoid factor
A test shows whether rheumatoid factor is detectable in your blood, and in what quantity.
With persistent joint complaints
For complaints that persist, rheumatoid factor is often included in the assessment. Keep coordinating that process with your GP.
Together with inflammation values
CRP and the sedimentation rate show whether there is inflammatory activity. Alongside rheumatoid factor, that gives a fuller picture than one value alone.
Ahead of a consultation
Those preparing for a conversation with their GP take the result along as a starting point for that conversation.
With a known predisposition in the family
If rheumatoid arthritis runs in your family, you may want to know how your own values stand.
Explanation of an earlier result
If you received a result earlier without much explanation, our doctor explains what the value does and does not say.
What your result means
Raised rheumatoid factor: what does your result mean?
Rheumatoid factor is measured in international units per millilitre (IU/mL) and is generally reported as positive or negative. The laboratory states the reference values and the cut-off that apply there alongside your result. This test measures antibodies, not the condition of your joints.
A low or undetectable value
If rheumatoid factor is not or barely detectable, that makes rheumatoid arthritis less likely. It cannot rule it out: part of the people with this condition have no detectable rheumatoid factor. If your complaints persist, that pattern of complaints remains leading for the next step, regardless of this result.
A value within the reference values
A rheumatoid factor within the laboratory's reference values is generally reported as negative. That gives a reassuring picture for this marker. It says nothing about other causes of joint complaints, nor about inflammatory activity; for that our doctor looks at markers such as CRP and the sedimentation rate.
An elevated value
A detectable or elevated rheumatoid factor means this antibody is present in your blood. That fits with rheumatoid arthritis, but is not a diagnosis in itself: rheumatoid factor also occurs in people without joint complaints, more often at older age, and in other conditions such as long-lasting infections, liver conditions and Sjögren's syndrome. The level of the value says little about severity. Our doctor explains what your result means and whether follow-up via your GP is customary, for example additional tests or assessment of the joints.
How we interpret your result
Our doctors interpret your rheumatoid factor against the laboratory's reference values and your personal context, such as age, complaints, family history, medication use and any known conditions. Where useful, they place the result alongside your inflammation values.
Related tests
Often combined with Rheumatoid factor.
A single marker gives one perspective. For a broader picture you can combine Rheumatoid factor with a theme package or related markers.
+ €29 blood draw fee per orderFree from €225
Frequently asked questions
Everything you want to know
Does a positive rheumatoid factor mean I have rheumatoid arthritis?
No. A detectable rheumatoid factor also occurs in people without joint disease, and that chance increases with age. In addition, the value can be elevated with long-lasting infections, liver conditions and Sjögren's syndrome. The diagnosis of rheumatoid arthritis is made by a doctor, based on complaints, physical examination and additional investigation together.
Does a negative result rule out rheumatoid arthritis?
No. Part of the people with rheumatoid arthritis have no detectable rheumatoid factor; this is called seronegative rheumatoid arthritis. If your complaints persist, that pattern of complaints is leading and assessment by your GP remains the starting point.
What is the difference from anti-CCP?
Anti-CCP is a different antibody test that is more specific for rheumatoid arthritis than rheumatoid factor. We do not currently offer anti-CCP. If you want that test, your GP or rheumatologist can request it, usually as part of a broader assessment.
Do I need to fast for this test?
No, you do not need to fast for rheumatoid factor. Do drink water normally, as you usually would.
Does the level of the value say anything about severity?
Barely. The level of rheumatoid factor does not track neatly with the severity of complaints or with the degree of inflammation. For inflammatory activity, markers such as CRP and the sedimentation rate are more informative, and these are often viewed together.
I have joint complaints, is this the right test?
Joint complaints have many causes, of which rheumatoid arthritis is one. Persistent, swollen or morning-stiff joints belong with your GP. This test can provide useful information alongside that, but does not replace that assessment.
How often can I have this measured?
A single determination is generally enough for insight. Rheumatoid factor changes slowly and repeat testing in the short term adds little. Within an ongoing treatment process, your treating doctor decides whether and when re-testing is useful.
What do I do with my result?
You receive a PDF report with your result and a personal explanation from a doctor. What you do with it, such as discussing it with your GP, remains entirely your choice.
Ready for insight into your rheumatoid factor?
You receive your rheumatoid factor including personal explanation from a doctor, typically within 2 working days. No referral required.
Order Rheumatoid factor →Want to test multiple markers at once?
Combine Rheumatoid factor with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from €225.
60,-
+ €29 blood draw fee+ €29 blood draw fee per order