Jennifer Freeman, MD
Jennifer Freeman, MD

Doctor of Medicine (M.D.) in 2008 from UT Health San Antonio, Surgeon at TRACC Dallas

Oct 27, 2018 4 min read

RA Diagnosis: What Criteria are used to Diagnose Rheumatoid Arthritis?

If a patient is showing early signs and symptoms of RA, a doctor can refer the patient to a rheumatologist – a physician who specializes in arthritis and other diseases of the joints, muscles and bones. The rheumatologist will work with the patient and the patient’s primary care physician to reach a RA diagnosis and provide treatment.

diagnosis

Because there is no exact known cause of RA, doctors look at a number of different factors before reaching a diagnosis. To reach a diagnosis, physicians follow a set procedure looking for multiple criteria, rather than one individual test. This includes examining physical symptoms, looking at family and personal medical history, and performing blood and other diagnostic tests (like x-rays or CT scans).

Some cases may be easier to diagnose than others, especially in the early stages of developing symptoms when symptoms may be less clear. Doctors work hard to ensure they’ve looked at all possibilities and that their examination and testing results are consistent with most cases of RA.

Symptoms

To begin the diagnostic process, doctors first look at symptoms. RA has a clear set of early signs and symptoms that lead doctors to consider it as a diagnosis. These initial symptoms include:

  • — Joint pain, stiffness and swelling for more than 6 weeks
  • — Swelling affecting 3-4 different joints or more
  • — Morning stiffness lasting longer than 30 minutes
  • — Symmetrical symptoms affecting both sides of the body
  • — Swelling and pain affecting the wrists, hands and finger joints
  • — Rheumatoid nodules developing under the skin

If these symptoms have been present for more than six consecutive weeks, doctors may consider these as symptoms specific to RA as opposed to other types of arthritis, like osteoarthritis. Doctors may also look for and ask about symptoms like fatigue, low-grade fever, loss of appetite, and even feelings of depression and malaise.

A full physical examination helps doctors find these symptoms and look at joints for tenderness, swelling, soreness, warmth, and redness. They will ask about difficulties moving joints and decreases in range of motion. Symptoms may come and go but typically, they do not. They remain noticeable and possibly progressive.

Family & Personal Medical History

The patient’s medical history and family history are important factors in helping to reach a RA diagnosis. Studies have shown that the average risk of someone in the general population developing RA is about 1%. However, if there is a family history of the disease, the risk of another family member developing RA increases.

When diagnosing RA doctors ask about the following:

  • — Patient’s family members who have or had RA
  • — Patient’s existing or past autoimmune disorders
  • — Patient’s family members with other autoimmune disorders
  • — Other medical conditions, illnesses or complications

Depending on each patient’s unique set of answers, it can help doctors identify factors that lead to a RA diagnosis.

Blood Tests

There are specific and general blood tests which help doctors reach the diagnosis of RA. The specific tests identify a specific set of antibodies that are known contributors of RA symptoms. The general blood tests look for overall inflammation levels in the body. When these results are placed together, they create an overall picture of a patient with RA (or without). These tests include:

  • — Rheumatoid factor
  • — anti-Cyclic Citrullinated Peptide (CCP)
  • — Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP)

Rheumatoid Factor

Rheumatoid factor is a type of antibody found in the majority of RA patients. If a patient tests positive for rheumatoid factor it helps to reach a diagnosis, but its presence doesn’t confirm it. Many patients with other autoimmune disorders and inflammatory conditions test positive for rheumatoid factor but don’t have rheumatoid arthritis.

Anti-CCP

If a patient tests positive for anti-CCP this is a strong indicator of RA. The anti-CCP antibodies can exist in a person’s system long before they ever exhibit symptoms of RA.

ESR and CRP

ESR and CRP are tests that doctors use to measure the level of inflammation in a patient’s joints. If a person indicates a certain level of inflammation and exhibits symptoms of RA, this becomes another very strong indicator of a possible RA diagnosis.

Imaging Scans

When a patient has strong and clear symptoms of RA, a doctor may also order a series of imaging scans. These include x-rays, CTs, MRIs, and possibly ultrasounds. In these imaging scans, doctors look for signs of joint damage. Bone and cartilage erosion as well as narrowing joint spaces can be signs of RA.

Reaching a RA Diagnosis

Once all of these steps have been conducted, doctors will look at all of the test results and reach a conclusion based on the overall picture. Some doctors take a more symptom based approach to diagnosing RA while others rely on blood tests and medical history to confirm a RA diagnosis.

This is why it’s possible to be diagnosed with RA but not test positive for antibodies or have a medical history of RA in your family. If the symptoms themselves are consistent with RA, then it can still be diagnosed.

That being said, the main criteria for diagnosing RA do not change. The patient must exhibit symptoms for greater than six weeks, symmetrical symptoms, as well as multiple joints being affected including fingers and hands.

Classifying RA Types

If a patient displays all the symptoms of RA and tests positive for antibodies then they can be diagnosed with seropositive RA.

However, if a patient displays all the symptoms of RA, but doesn’t test positive for antibodies, the doctors can make a seronegative RA diagnosis.

Read more about the types of rheumatoid arthritis here.

Other Factors

RA symptoms (especially in early stages) can be mistaken for other conditions. Doctors work to rule out the potential of other illnesses when they are first alerted to possible signs of RA. Once these conditions have been ruled out, it makes it easier to reach a RA diagnosis. Some of these conditions include:

  • Other forms of arthritis including osteoarthritis
  • Lupus
  • Lyme disease
  • Gout
  • Fibromyalgia
  • Still’s disease

Due to the ambiguous nature of many RA diagnoses, researchers are continually looking for links and similarities between disease symptoms and patients’ genetics and medical histories. While diagnosing RA is difficult and can be complicated, the most important thing is to detect symptoms early and begin treatment as soon as possible.