1. RA can be difficult to diagnose

RA is a complex disease, and symptoms may develop months before diagnostic tests show inflammation. RA also can be confused with other conditions. 

2. RA has some hallmark signs

One way a doctor can diagnose RA is by taking a full medical history and hearing the patient's symptoms. Among the common signs of RA are morning stiffness, three or more painful joints, involvement of both sides of the body and subcutaneous nodules.

3. Blood tests can help diagnose RA

Several blood tests can help diagnose RA by detecting inflammation and antibodies. They can also help predict severity and complications of the disease. These tests include Rheumatoid Factor, Erythrocyte Sedimentation Rate, C-Reactive Protein and Anti-CCP Antibody. 

 4.But blood tests aren't definitive

Keep in mind that blood tests alone can't definitively indicate that a person has RA. In some cases, in fact, people who do have RA will have normal blood tests. This is called sero-negative RA. 

5. Imaging tests can help with diagnosis

While X-rays aren't able to detect early RA because they can't show images of soft tissue, they can capture the progression of joint damage over time. Ultrasound, MRI and dexa scans may also be used to provide more information about changes in a person's body. 

6. Other disorders have similar symptoms

Several other conditions mimic the symptoms of RA. Some are similar diseases, such as psoriatic arthritis, which is also an autoimmune disease that attacks the joints. Gout and osteoarthritis can sometimes be confused for RA as well, but they are very different conditions. 

7. Early diagnosis is critical

Getting a diagnosis as early as possible is key to halting joint damage. An early aggressive treatment plan can be critical to getting RA under control and preventing further damage. 

Source: healthcentral.com