How Rheumatoid Arthritis is Diagnosed

There is no single test for RA which can be difficult to diagnose, doctors generally rely on various types of blood test and imaging techniques as well as a physical examination of the affected joint. The synovial fluid may also be analysed in order to determine the extent of damage to the joint.

The European League Against Rheumatism (Eular) has produced a set of recommendations on the managment of early arthritis. The first recommendation indicates that all patients with more than one affected joint should see a rheumatologist within six weeks after the onset of symptoms.

Doctors should conduct a physical examination to look for discomfort, swelling and redness around the affected joints. A patient history should be taken and a number of tests carried out in order to exclude other diagnoses.

Blood Tests.

In making a diagnosis doctors may use one or more of the following blood tests-

• Erythocite Sedimentation Rate (sed rate) which measures the rate at which red blood cells settle in a test tube.
• C-Reactive Protein(CRP), higher than normal levels of CRP in the blood indicate either inflammation or a bacterial infection such as rheumatic fever.
• Rheumatoid Factor(RF) is a test to acertain whether there are a high number of RF antibodies in the blood. Rheumatoid arthritis is the most common explanation for a heightened RF factor but it is also an indicator of lupus, scleroderma, Sjogren's syndrome and vasculitis. It is also important to note that only about fifty per cent with RA will have heightened RF scores when the disease starts.
• Anti-Cyclic Citrullinated Peptide Antibodies (anti-CCP) A recent study concluded that "Anti-CCP antibody status at the time of diagnosis is a valuable predictor of of the disease course in early RA." The study also indicated that a positive result for anti-CCP predicted higher disease activity in the three years following diagnosis.

Imaging Techniques.

X-rays of affected joints are useful in distinguishing between RA and osteoarthritis. Early stage RA may not be discernible by x-ray. X-rays of the feet are sometimes taken as affected joints show up here sooner than other parts of the body.

Bone loss at the edge of the joints is usually the first sign to be seen. Early joint x-rays may be useful as a benchmark in relation to the progress of RA.

Results obtained by MRI scanning and ultrasound are described by EULAR as promising. Further research is needed to establish the effectiveness of these two techniques before they become part of standard practice.

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