Rheumatoid arthritis diagnosis is accomplished by conducting a number of tests and matching a patient to established criteria as rheumatoid arthritis manifests on something of a spectrum.
RA Diagnosis: Blood Testing
If a patient is thought to possibly have RA, a number of blood tests may be ordered to look at different variables that might indicate compromised immunity, the presence of certain antibodies and also to help isolate other illnesses that the patient may have that can produce RA-like symptoms.
One test that is done is to check for an antibody known as Rheumatoid Factor or RF. An elevated rheumatoid factor may be found in several autoimmune diseases such as Sj繹gren's syndrome. About 80% test positive for RF but a negative test result does not exclude the possibility of RA; it simply places the arthritis in a category called seronegative rheumatoid arthritis.
Testing for RF is only a part of rheumatoid arthritis diagnosis since up to 1 in 10 healthy people display elevated rheumatoid factor.
As RA progresses, it is common to see the patient begin to come up positive for RF in later tests.
More specific testing has been developing which checks for certain antibodies more indicative of RA. The most recent tests are much more sensitive and specific. Additional tests are often administered in order to rule out other possible causes of the arthritis.
RA Diagnosis Criteria
Recently, new criteria for rheumatoid arthritis diagnosis were collaboratively put into effect by professional rheumatology bodies in Europe and the US.
RA diagnosis is established by scoring the patient on a scale of 1-10. 6 or above is a definite RA diagnosis.
The scoring takes into account the patient's joint health (which joints and how many are affected), serology (rheumatoid factor, anti-citrullinated protein antibody presence), length of time the patient is experiencing the arthritis and acute phase reactants.
Clinical RA Diagnosis
Physicians will typically look for the involvement of several joints and stiffness joints in the mornings as potential indicators of the presence of RA. Further, the patient is likely to be tested for elevated rheumatoid factor as well as possibly undergoing more recently developed tests prior to deciding upon RA treatment
RA Differential Diagnosis
The symptoms of RA are similar to the symptoms of several other diseases. For this reason it is necessary to isolate factor specific to RA to establish a diagnosis. Some of the diseases that can look like RA are:
Osteoarthritis (see: Osteoarthritis vs Rheumatoid Arthritis)
And several others. Doctors will typically order several tests in order to come closer to (or move further away from) a rheumatoid arthritis diagnosis.