Rheumatoid Factor (RF) Blood Test
Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects millions of people worldwide. Early and accurate diagnosis of RA is crucial for initiating timely treatment and improving patient outcomes. In recent years, testing and monitoring the rheumatoid factor (RF) biomarker have emerged as powerful tools in RA diagnosis and investigation.
Testing and monitoring RF levels play a pivotal role in the diagnosis and management of RA. Here are key reasons why it's important to utilise RF testing:
The discovery of rheumatoid factor (RF) marked the identification of the first autoantibody found in individuals with rheumatoid arthritis (RA). Autoantibodies, which develop in response to the body's own tissues, are characteristic of autoimmune diseases like RA. However, despite its name, RF is not exclusive to RA, and there are various factors that can influence RF lab results. It is worth noting that around 20% of individuals with confirmed RA may not exhibit abnormal RF test results, while approximately 5% of people without RA may show abnormal RF test results. Thus, negative RF levels do not rule out the presence of the disease, and positive levels do not guarantee an RA diagnosis.
The normal range of RF is typically defined as 0-30 IU/ml. RF levels exceeding 20 IU/ml alone are not sufficient for diagnosing RA, as there are other factors that can contribute to an elevated RF level. Several conditions and medical procedures can result in increased RF levels, including other autoimmune diseases, certain chronic infections, diabetes, bacterial endocarditis, cancer, normal aging, vaccinations, and transfusions. It is important to note that even if the disease goes into remission, an elevated RF level often persists once it has been detected.
Interpreting RF test results involves understanding reference ranges and values associated with the test. Here's a breakdown of RF values interpretation.
1. Negative: RF levels below the upper limit of the reference range indicate a negative result. While this suggests a lower likelihood of RA, it does not rule out the disease entirely, as some individuals with RA may have seronegative results.
2. Low Positive: RF levels slightly above the upper limit of the reference range may be considered a low positive result. Further investigation, including additional diagnostic tests, is typically recommended to confirm the presence of RA.
3. Moderate Positive: RF levels significantly exceeding the upper limit of the reference range strongly suggest RA. Combined with clinical evaluation, a moderate positive result aids in establishing a confident diagnosis.
4. High Positive: RF levels well above the upper limit of the reference range are highly indicative of RA. Such results are often associated with more severe disease manifestations, increased joint damage, and a need for aggressive treatment.
You can track your RF biomarker in the Health Dashboard.
While RF testing is a valuable tool, it does have limitations that need to be considered:
When obtaining blood samples for RF testing, you have a choice between capillary and venous samples. Here's an overview of their differences:
Testing and monitoring the rheumatoid factor biomarker have revolutionised the diagnosis and investigation of rheumatoid arthritis. RF testing plays a crucial role in early diagnosis, confirmation of RA, prognostication, treatment decision-making, and monitoring disease activity.
However, it is essential to consider the limitations of RF testing and interpret results in conjunction with clinical findings. By embracing RF testing and leveraging its benefits, you can enhance RA management and improve outcomes.