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Rheumatoid factor: all the info


Is calledRa-Test(Reuma test orrheumatoid factor) and is a blood test that can be used in the diagnosis of someautoimmune diseases.

How much does the Ra-Test cost?
The Ra-Test consists of a blood test and its cost depends on the clinical center of reference. Generally, the cost is 5 - 7 euros. It is a relatively inexpensive and minimally invasive test. The cost of the sample must be added to the cost of the test.

Rheumatoid factor: what it is

Therheumatoid factor(FR) is an autoantibody, that is an antibody produced by our immune system which attacks the tissues of our organism. This is the basic characteristic of all autoimmune diseases: a targeted attack on our body by antibodies produced by our own immune system. In the article "autoimmune diseases: what they are"We showed you the list of autoimmune diseases based on the tissues attacked.

Rheumatoid factor: reference values

Positive and negative rheumatoid factor.
The Rheumatoid factorit is positive in rheumatoid arthritis, Sjogren's syndrome, SLE, scleroderma, connective tissue diseases, tumors, in the elderly, in chronic active liver diseases ... and in other pathophysiological conditions.

It is important to emphasize that not all subjects with rheumatoid arthritis or other autoimmune diseases have detectable serum levels ofrheumatoid factor. This means that even if the test result isnegativethere may be an ongoing autoimmune disease. This is why diagnosing autoimmune diseases is not easy at all and one must strictly follow the advice of an expert.

High rheumatoid factor

Before talking about reference values,high rheumatoid factororvery high, it is important to understand this:only a rheumatologist can make a diagnosis and can carefully interpret the symptom picture reported by the patient and the results of the analyzes.

High rheumatoid factor: a level above 20 IU / mL is reported "high". Thesevaluesthey are indicative for rheumatoid arthritis and Sjogren's syndrome.

Therheumatoid factorresults "high" or "very high" even in the case of chronic viral infections, leukemia, dermatomyositis, mononucleosis, chronic hepatitis, Hashimoto's thyroid and others autoimmune diseases such as lupus erythematosus and scleroderma. For this reason, we reiterate once again that the result of thera-testit should only be interpreted by an expert, it can be the beginning of a diagnosis but cannot provide absolute conclusions.

To complicate everything there are thereference valueswhich can vary from laboratory to laboratory! If you are looking forreference valuesbetter ask for them at the Analysis Laboratory you contacted or speak directly with your doctor.

While some laboratories set a reference value for therheumatoid factorshigher than 20 IU / mL (> 20 IU / mL), other analysis laboratories asknormal valuesbelow 23 IU / mL (<23 IU / mL). The sensitivity and specificity of the rheumatoid factoris low to determine a certain diagnosis, so thera-test it can be seen as an orientation point of reference.

In addition, "false positives" occur in 5% of cases.

A study in Denmark found that people with avery high rheumatoid factor(RA> 23 IU / mL) have an increased risk (even in the long term) of contracting rheumatoid arthritis.

Low rheumatoid factor

A low rheumatoid factor it can lower the risk of incidence of rheumatoid arthritis and other autoimmune diseases, but as stated, in some cases it is possible to see “low rheumatoid factor” values ​​which also lead to a diagnosis of rheumatoid arthritis or other autoimmune diseases. This is why this single test cannot be the only diagnostic element.

A detected value of less than 20 IU / mL (<20 IU / mL) is reported as "normal" or "low". Also in this case, some laboratories may take different reference values ​​and for this it is essential to consult a rheumatologist.

Rheumatoid factor and other values ​​to be evaluated

To diagnose an autoimmune disease, therheumatoid factoror thera-testthey are not the only parameters to be evaluated. A good rheumatologist or immunologist will be able to prescribe specific blood tests for you.

Typically, to investigate the presence of a autoimmune diseasesector specialists make use of the so-called "first level tests". These exams are:

  • Complete blood count
  • Fibrinogen
  • PCR
  • VES
  • Complement components (C3, C4 and anti C1Q)
  • Rheumatoid factor
  • Urinalysis
  • Ana (anti-nuclear antibodies)

The blood count as well as the ESR, CRP and urine tests are used by your doctor to assess your general health condition. These analyzes are essential to avoid the presence of other alterations. Rheumatoid factor, complement components, anti-nuclear antibodies as well as rheumatoid factor itself, are tests that can show a clinical picture similar to that found inautoimmune diseases.


Video: Rheumatoid Arthritis - Signs u0026 Symptoms. Johns Hopkins Medicine (May 2021).