There are many kinds of tests that can be done to diagnose rheumatoid arthritis (RA). X-rays, CT scans, MRIs, and lab tests all have some value. Physicians must choose carefully to avoid unnecessary costs while still getting an accurate diagnosis.
Early identification of RA is important now that there are drug therapies that can prevent joint damage when used right away. Once erosion of the joint cartilage occurs, irreversible disability can happen. To avoid this, early diagnosis and treatment of this condition is very important.
In this article, rheumatology experts review early warning signs of RA. And they offer an update on testing procedures for quick and accurate diagnosis. Patients with pain, swelling, and warmth in the small joints of the hands and feet are suspected of RA. A positive family history of RA is a red flag.
Blood tests for rheumatoid factor and a positive anti-CCP test give early clues to the presence of RA. Antibodies against cyclic citrullinated peptide (CCP) are specific for RA.
A positive anti-CCP test is possible in many people with RA before they have any symptoms. In fact, a positive anti-CCP test is a predictive risk factor for damaging joint erosive disease later in the disease process.
Other serologic (blood) markers for RA include C-reactive protein (CRP) and genetic markers such as human leukocyte antigen (HLA). Elevated CRP is not an early warning sign, but is present when inflammation occurs. Testing for a particular HLA called the HLA-DR4/DR1 cluster may help predict severity of disease. This test is still experimental. It isn’t available yet on a routine basis.
X-rays are easy and readily available but they only show structural damage after the fact, rather than before. Still, baseline images can be digitally stored and retrieved later for comparison to measure disease progression.
MRIs and ultrasound (US) are much better at identifying soft tissue changes and joint pathology early in the disease process. Although more expensive, neither of these tests exposes the patient to ionizing radiation.
Studies show that bone erosion shows up on MRIs a full year before they are seen on X-rays. And MRIs can help show progressive changes in patients without symptoms who are taking disease-modifying antirheumatic drugs (DMARDs). This gives the physician a chance to change the drug dose in order to prevent further joint damage.
Currently, MRIs are not routinely used in this way. More study is needed to justify the cost. Specific guidelines need to be developed for its use in clinical practice. For now, it remains a research tool.
A more practical imaging tool may be ultrasound. It’s safe, noninvasive, and portable. It is also less expensive than CT scans or MRIs. It’s more sensitive than standard X-rays. In the hands of a well-trained health care professional, ultrasound can give an accurate picture of joint pathology. In Europe, it is used when X-rays are negative but the physician suspects RA. It can also be used to monitor effectiveness of drugs.