If rheumatoid arthritis (RA) is left untreated, inflammation from the condition can start to develop in other areas of the body, causing various and sometimes serious complications that can affect other organs — such as the heart, lungs, eyes, and nerves — and could cause significant long-term disability.

If you're experiencing rheumatoid arthritis symptoms, it's important to get diagnosed as soon as possible so that you can receive prompt treatment. For many people, functional disability — trouble with everyday routines, such as dressing, eating, and walking, caused by joint damage — often occurs one to two years before actual diagnosis. These issues may be a signal that you have RA.

Rheumatoid Arthritis Initial Diagnosis

There is no single test that can definitively diagnose RA.

As with other illnesses, diagnosis of RA typically begins with your doctor getting your medical history and conducting a physical exam.

You doctor will begin by asking questions about the symptoms you're experiencing, including when and how they occur and how they've changed over time (if they have). One specific symptom they will ask about is morning joint stiffness that lasts for at least 30 minutes and occurs in the peripheral joints rather than the lower back — a common RA symptom.

Morning stiffness is typically severe enough to interfere with physical functions after waking up.

The other main symptom is swelling of the joints that lasts for at least six weeks, particularly if the swelling occurs on the same joints on both sides of the body. Swelling that occurs for less than six weeks could be a sign of multiple different things; an example is acute viral polyarthritis, an inflammation of the joints caused by a virus.

Your doctor will also ask about any other medical conditions you have — people with RA frequently have co-occurring conditions, such as cardiovascular disease — and about those of your immediate family members, too.

You have more than double the risk of developing RA than the general population if you have a first-degree relative (parent, offspring, sibling) with RA, according to a study published in November 2019 in the journal Arthritis Care & Research.

And your risk also greatly increases if you have a family history of inflammatory bowel disease, lupus, scleroderma, or thyroid disease.

During your physical exam, your doctor will look for signs of tenderness, swelling, warmth, and pain in your joints, and check to see if you have any movement limitations. Joint swelling in RA is typically "soft," compared with the "hard" (bony) swelling of osteoarthritis.

They will also check for rheumatoid nodules, or noticeable bumps that often occur at the base of arthritic joints, such as the elbows.

These nodules affect up to 30 percent of patients, according to research published in the journal Autoimmunity Reviews.

Following those initial diagnostic procedures, your doctor will order blood tests.

Tests for Rheumatoid Factor and Other Antibodies Are Used to Diagnose Rheumatoid Arthritis

Rheumatoid arthritis is typically defined as being either "seropositive" or "seronegative," referring to the presence of specific antibodies in the blood. Rheumatic nodules occur almost exclusively in people with seropositive RA.

Previously, patients were considered seropositive if they had the antibody rheumatoid factor, or RF. But these antibodies are found in only 80 percent of people with RA.

What's more, RF is also found in people with numerous other conditions — including some infections (mononucleosis, tuberculosis), other inflammatory or autoimmune conditions (lupus, Sjögren's syndrome, scleroderma), and certain cancers (leukemia, multiple myeloma) — so its presence doesn't necessarily indicate RA.

Today, a more sensitive test for seropositivity is available. This test looks for anti-citrullinated protein antibodies (ACPAs), a collection of autoantibodies — antibodies that target and react to a person's own proteins, mistaking them as foreign. To detect ACPAs, the test looks for evidence of the antibodies' immune system reactivity with compounds called cyclic citrullinated peptides (CCPs), which are fragments of natural human proteins undergoing a certain type of molecular change.

About 60 to 70 percent of people with RA have these so-called anti-CCPs, and these antibodies can show up years before symptoms develop, according to the Arthritis Foundation.

Compared with RF, anti-CCP is a more specific marker of the disease, and high levels of anti-CCP antibodies may indicate a greater RA severity.

In recent years, researchers have identified a number of different ACPAs, detected through the anti-CCP tests. A study published in June 2018 in the journal Annals of the Rheumatic Diseases found that no single ACPA is responsible for RA joint damage and inflammation.

Rather, having a number of different ACPAs is associated with a number of markers of joint destruction and inflammation, according to the study. This suggests that the anti-CCP tests may be able to help clinicians determine who will develop greater joint damage.

Though RF and anti-CCP antibody tests are highly informative and can help with diagnoses, they're not enough to diagnose RA alone.

Up to half of patients don't have both RF and anti-CCP antibodies when initially tested, and 20 percent of people who are found to have RA never test positive for the antibodies, according to the Hospital for Special Surgery.

Other Tests for Seropositive Rheumatoid Arthritis

Blood tests are not only used to detect RF and anti-CCP antibodies. They're also used to reveal if you have:

Anemia, or low red blood cell count, which occurs in up to half of people with RA
A high erythrocyte sedimentation rate, also known as a sed or ESR rate, a crude measure of inflammation in your body
High C-reactive protein (CRP) levels, another marker of inflammation

Like the antibody tests, these tests alone cannot diagnose RA. The ESR rate, for instance, is not specific to RA inflammation and can also be influenced by infections and age. And CRP, which is also not specific to RA, can be influenced by obesity and infection.

But a high ESR or CRP, when combined with other clues, can help make an RA diagnosis.

Aside from blood tests, an X-ray can help your doctor determine the degree of destruction in your joints, but may only be useful when RA has progressed to a later phase.

In recent years, ultrasound and magnetic resonance imagery (MRI) scans have improved RA diagnosis by helping to detect joint inflammation, erosion, and fluid buildup. Ideally, however, doctors would want to diagnose and begin treating RA before structural damage shows up in imaging tests.

How Is Seronegative Rheumatoid Arthritis Diagnosed?

Some patients still have RA but do not test positive for either anti-CCPs or RF — they have seronegative RA.

This form of RA is often more difficult to diagnose, and also usually produces milder symptoms than seropositive RA. The genetic links, environmental risks, and responsiveness to medications of seronegative RA also differ from seropositive RA. A study published in March 2020 in the Annals of the Rheumatic Diseases shows that seronegative RA is becoming more common, jumping to 20 out of 10,000 people with RA between 2005 and 2014 from 12 out of 10,000 between 1985 to 1994.

To diagnose seronegative RA, your doctor may conduct more tests to rule out other possible causes of your symptoms, such as osteoarthritis — which is sometimes misdiagnosed. Though osteoarthritis may produce similar symptoms to RA, osteoarthritis is a degenerative joint disease that develops from "wear and tear" instead of inflammation related to autoimmune issues.

Your doctor may test your blood for infections, including human parvovirus B19, hepatitis B, hepatitis C, and Lyme disease. These issues can produce RA-like symptoms. They may also analyze the fluid within your joints to detect abnormalities and high white blood cell counts.

Your doctor may also conduct a synovial biopsy, which involves removing a small piece of the tissue lining one of your joints.

But even with these tests, a correct diagnosis of seronegative RA isn't guaranteed. The results of your joint fluid tests, for example, may instead indicate that you have chronic gout. And your doctor may diagnose you with psoriatic arthritis if you later develop a skin rash.

Other diseases that may resemble seronegative RA include reactive arthritis and ankylosing spondylitis, a form of chronic inflammatory arthritis that primarily affects the spine.

Preclinical Rheumatoid Arthritis

Some people are highly at risk of RA but don't yet have the condition — instead, they may have preclinical RA.

People with preclinical RA have the biomarkers (RA or anti-CCP) of RA but don't have the hallmark joint inflammation associated with the disease. Research suggests that tests can detect these biomarkers and autoantibodies three to five years before RA joint systems arise.

But that's not to say people with preclinical RA are free of health issues. They may have mild aches and pains, joint swelling on a single side of the body, or some nondescript fatigue or malaise, as well as a higher risk of heart attack, heart failure, depression, and mood disorders. One study found that people with preclinical RA had a 24 percent increased risk of having a cardiovascular event over a 10-year period.

For those with preclinical RA, disease-modifying antirheumatic drugs, which are used to treat RA, can significantly reduce RA risk, according to a meta-analysis published in August 2018 in the Annals of the Rheumatic Diseases.

Diagnosing Rheumatoid Arthritis With Infrared Light

In the near future, physicians may be able to diagnose RA with a noninvasive procedure using infrared light.

In a pilot study published June 20, 2019, in the Journal of Biomedical Optics, researchers found that the technique, which involves placing a person's hand in an infrared scanner, can accurately detect markers of RA inflammation.

But experts argue that the technique is not ready for clinical use, as it cannot make a definitive diagnosis of RA and cannot distinguish between different types of RA.

Editorial Sources and Fact-Checking

Patient Education: Rheumatoid Arthritis Signs and Symptoms. UpToDate. March 2017.
Diagnosis and Differential Diagnosis of Rheumatoid Arthritis. UpToDate. August 8, 2017.
Kronzer et al. Family History of Rheumatic, Autoimmune, and Nonautoimmune Diseases and Risk of Rheumatoid Arthritis. Arthritis Care & Research. November 2019.
What Is the Criteria to Diagnose Rheumatoid Arthritis? What Patients Need to Know. CreakyJoints. October 15, 2020.
Aletaha D, Smolen JS. Diagnosis and Management of Rheumatoid Arthritis. Journal of the American Medical Association (JAMA). October 2018.
Prete M, Racanelli V, et al. Extra-articular Manifestations of Rheumatoid Arthritis: An Update. Autoimmunity Reviews. December 2011.
Rheumatoid Arthritis Signs and Symptoms. Johns Hopkins Arthritis Center.
Rheumatoid Factor (RF) Test. MedlinePlus. December 3, 2020.
Kurowska W, et al. The Role of Anti-Citrullinated Protein Antibodies (ACPA) in the Pathogenesis of Rheumatoid Arthritis. Central European Journal of Immunology. December 2017.
Rheumatoid Arthritis: Causes, Symptoms, Treatments and More. Arthritis Foundation.
Sohrabian A, et al. Number of Individual ACPA Reactivities in Synovial Fluid Immune Complexes, but Not Serum Anti-CCP2 Levels, Associate With Inflammation and Joint Destruction in Rheumatoid Arthritis. Annals of the Rheumatic Diseases. June 2018.
Understanding Rheumatoid Arthritis Lab Tests and Results. Hospital for Special Surgery. March 26, 2018.
Myasoedova et al. Is the Epidemiology of Rheumatoid Arthritis Changing? Results From a Population-based Incidence Study, 1985–2014. Annals of the Rheumatic Diseases. March 2020.
Seronegative RA: What Are the Symptoms of Seronegative RA? RheumatoidArthritis.org.
What Exactly Is Seronegative Rheumatoid Arthritis? Key Facts You Need to Know. CreakyJoints.
Liang KP, et al. Autoantibodies and the Risk of Cardiovascular Events. Journal of Rheumatology. November 2009.
Hilliquin S, et al. Ability of Disease-Modifying Antirheumatic Drugs to Prevent or Delay Rheumatoid Arthritis Onset: A Systematic Literature Review and Meta-Analysis. Annals of Rheumatic Diseases. July 2018.
Lighter D, Filer A, Dehghani H. Detecting Inflammation in Rheumatoid Arthritis Using Fourier Transform Analysis of Dorsal Optical Transmission Images From a Pilot Study. Journal of Biomedical Optics. June 2019.

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Rheumatoid Arthritis (RA)

Rheumatoid Arthritis Diagnosis