Is there a single blood test to diagnose rheumatoid arthritis?
The simple answer is: no! According to the American College of Rheumatology (ACR), “There is no one test to diagnose RA!” Unfortunately, all too often patients experiencing symptoms of rheumatoid arthritis experience delays in diagnosis due to many factors, including the myth that there is a single blood test for RA.
Rheumatoid arthritis (RA) is actually diagnosed most often by rheumatologists, medical doctors who specialize in the diagnosis and treatment of musculoskeletal and autoimmune conditions. They look at the following four factors, among others:
1) Physical Examination
During a physical examination, a rheumatologist will often feel your joints, assess how swollen and warm they are, and determine if they have any restrictions. They may also feel for rheumatoid nodules.
They may also have you report if you feel pain or tenderness as they press on specific parts of your joints. (Citation: Arthritis Foundation Rheumatoid Arthritis information page).
2) Bloodwork & Imaging
While bloodwork is not the *only* factor that is used to determine a diagnosis of rheumatoid arthritis, it is definitely an important part of a comprehensive evaluation for rheumatoid arthritis.
- Rheumatoid factor (RF) is an antibody found in approximately eighty percent of people with Rheumatoid arthritis eventually, but found in as little as 30% of people at initial diagnosis of RA according to the American College of Rheumatology.
- Anti-CCP: This test measures antibodies to cyclic citrullinated peptides (pieces of proteins), or anti-CCP for short. A positive result is found in 60 – 70% of patients with RA, but can also be found in people who don’t have RA (citation).
- If you are positive for rheumatoid factor, you may be referred to as “Seropositive.” Some also consider a positive anti-CCP (see below) when labeling a patient as “seropositive.” (citation)
- Antinuclear antibody (ANA) testing is a general measure of autoantibodies, or antibodies your immune system has made against your own healthy tissue. It is positive in 95% of patients with lupus and 50% of patients with rheumatoid arthritis (citation). However, ANA may be positive in those who don’t have autoimmune disease. (citation)
- Erythrocyte sedimentation rate (ESR) is a general inflammation marker, which is usually high in people who have rheumatoid arthritis.
- Serum C-reactive protein (CRP) – this is a general measure of inflammation and is not specific to rheumatoid arthritis (citation), however doctors will often order it to measure overall inflammation.
- Complete blood count (CBC) with differential and platelet count: this is a general screening test that can give a good picture of a patient’s overall health status (citation). It can also determine whether a patient is anemic, which is more common with RA.
- More blood tests: VECTRA (note this is not diagnostic but may be ordered), 14-3-3η (eta) protein, tests of liver and kidney function, urine analysis and more may be ordered.
- Imaging to assess for rheumatoid arthritis may include ultrasound, X-Ray, MRI and more (learn more here).
3) Personal & Family Medical History
The Rheumatologist may ask if anyone in your family has rheumatoid arthritis or an autoimmune disease. If the answer is yes, they will often want to know which autoimmune condition, when did it start, how severe was it, and what treatment did they receive? (citation)
They also ask about your personal medical history – for example, did you have an injury or illness before your rheumatoid arthritis symptoms started? Do you have any other chronic health issues? (citation)
4) Your report of symptoms:
At the initial evaluation appointment for rheumatoid arthritis, it’s very important for the patient to share the pattern of their current symptoms. When did your pain start, and where is it? Is it constant or does it come and go? How severe is it, and what kind of pain is it – dull ache, sharp stabbing pain, tingling, or something different? What about systemic symptoms, like fatigue, weakness or fever? Learn more about symptoms that rheumatologists like to know about at the initial evaluation appointment here.
The typical pattern of RA is as follows:
- Joint symptoms including: Pain, tenderness, swelling or stiffness in more than one joint (may be hot pain or dull ache)
- Location: small joints of the hands, wrists and/or feet, usually symmetrically,
- Duration: lasted for six weeks or longer, with a pattern of morning stiffness that lasts for 30 minutes
- PLUS systemic symptoms including: fatigue, fever, weight loss, and/or weakness (learn more about systemic symptoms here).
If your primary care doctor says they did “the blood test” for RA and refuses to refer you to a rheumatologist:
With everything above in mind, it’s easy to see how the diagnosis of rheumatoid arthritis is not as clear cut as a simple blood test. Sadly, many patients experience delays in diagnosis due to many factors , sometimes including being told by a provider that they won’t refer to a rheumatologist because the patient’s bloodwork is “normal,” which could simply be a case of seronegative rheumatoid arthritis (learn more here and also here.)
If you have many symptoms of rheumatoid arthritis and would like to educate your provider about the importance of a specialist evaluation by a rheumatologist, you may want to consider sharing “How is rheumatoid arthritis diagnosed?” section of the American College of Rheumatology’s information page for rheumatoid arthritis, which states: “There is no one test to diagnose RA.”
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