Ruling out other conditions that mimic RA, such as Lyme disease, lupus, and fibromyalgia is part of diagnosing RA. This process relies on a combination of your physical examination, medical history, laboratory test results, and imaging studies.
Even after you’ve been diagnosed with RA, your healthcare providers may consider other conditions if your symptoms are still not improving, despite treatment with disease-modifying anti-rheumatic drugs (DMARDs).
It’s also possible that you could have RA and another condition.
Osteoarthritis
The most common type of arthritis, osteoarthritis (OA), is a degenerative joint disease that can be similar to RA.
Some key differences between OA and RA include:
The absence of systemic inflammation symptoms with OA Onset in older adulthood with OA OA affects different joints than RA (for example, the end joints of the hands are commonly involved in OA but not usually involved in RA) An asymmetrical pattern of joint involvement with OA With RA, prolonged morning stiffness typically lasts for over 45 minutes, while morning stiffness in OA often lasts for less than 30 minutes. OA pain typically gets worse with activity, while RA pain often improves
Blood work and imaging tests can help your healthcare provider hone in on an accurate diagnosis. Rheumatoid factor (RF) is usually present in RA but not in OA, and RA and OA have distinctly different radiographic appearances.
Psoriatic Arthritis
Psoriatic arthritis (PA) and other spondyloarthropathies can present similarly to RA, but can often be distinguished through blood work.
High levels of rheumatoid factor (RF) or anti-citrullinated peptide (anti-CPP) antibodies are typically present in RA. These results are considered seropositive.
PA, reactive arthritis, ankylosing spondylitis, and inflammatory bowel disease–associated arthropathy do not have these indicators (seronegative).
In addition, RA typically starts in the fingers and toes, whereas PA and other spondyloarthropathies can affect the spine and the sacroiliac joints.
Other key characteristics of PA that help differentiate it from RA include:
Asymmetrical joint involvement Absence of small-joint disease A sausage-like appearance of fingers or toes Psoriatic rash, which may or may not be present
Viral Arthritis
Viral infections such as rubella, parvovirus B19, HIV, and hepatitis B and C can cause pain and swelling in multiple joints (polyarthritis) and present in a way that’s clinically similar to rheumatoid arthritis.
Viral arthritis can often be distinguished from RA by a rash and a history of exposure to specific viruses. For example, recent travel to Italy, India, Indian Ocean islands, or the Caribbean could have led to exposure to the mosquito-borne alphavirus chikungunya, which presents as joint pain, fever, and a rash.
Your healthcare provider can take blood work to rule out different viral and bacterial causes of joint pain. Treatment for viral arthritis is normally focused on pain management. And HIV-triggered arthritis can be relieved with combination antiretroviral therapy.
Most cases of viral arthritis resolve on their own after several weeks.
Lyme Disease
Lyme disease is a tick-borne illness caused by the bacteria Borrelia burgdorferi or Borrelia mayonii. It presents with joint pain and swelling but can be mistaken for RA. The first sign of Lyme disease is a bull’s-eye rash (present in 70% of cases) that appears three to 30 days after a bite from an infected tick.
Left untreated, Lyme disease results in chronic arthritis with severe joint pain and swelling, particularly in the knees and other large joints.
Other signs of Lyme disease that aren’t present in RA include:
Severe headaches and neck stiffness Loss of muscle tone or drooping on one or both sides of the face Intermittent pain in tendons, muscles, joints, and bones Heart palpitations or an irregular heartbeat Dizziness or shortness of breath Shooting pains, numbness, or tingling in the hands or feet
Early treatment of Lyme disease with antibiotics typically results in complete recovery, though symptoms can linger for up to six months. A delay in antibiotic treatment can make the disease more difficult to treat and may result in chronic symptoms and pain, so it’s important that any symptoms be investigated.
Fibromyalgia
Fibromyalgia, a chronic pain condition, can be misdiagnosed as RA or another rheumatic condition. Both RA and fibromylagia can involve symmetrical joint pain and stiffness, but with fibromyalgia, the pain occurs at rest and not exacerbated by joint use.
Imaging studies are useful for distinguishing the conditions because synovitis (inflammation of joint lining) is present with RA and absent with fibromyalgia. In addition, blood tests for fibromyalgia are seronegative.
Fibromyalgia also differs from RA because it causes:
Fatigue and tiredness Brain fog Anxiety and depression Headaches Irritable bowel syndrome Numbness or tingling in the hands and feet Jaw pain and temporomandibular joint disorders (TMJ) Sleep problems
Fibromyalgia can be difficult to diagnose. There are no specific tests to confirm a diagnosis and, much like with RA, it is important to rule out other possible conditions.
Lupus and Scleroderma
The autoimmune diseases systemic lupus erythematosus and scleroderma often present with joint involvement that mimics rheumatoid arthritis. While lupus and scleroderma are two different diseases, they often overlap with one another.
One key difference between arthritis and lupus/scleroderma is the source of joint pain and deformity.
People with lupus and scleroderma may also test seropositive, so blood work may not help differentiate between them and RA.
Other signs of lupus and scleroderma that aren’t common in arthritis include:
Raynaud’s phenomenon—painfully cold fingers and toes with a pale-white or blue hue associated with impaired circulation Esophageal dysfunction or other digestive problems Sjögren’s syndrome, which affects fluid-producing glands, such as tear glands and salivary glands
Gout
Crystal-deposition diseases like gout and pseudogout are often mistaken for RA. With these conditions, uric acid crystal deposits settle around affected joints, resulting in inflammation and tissue damage.
Gout tends to appear as painful, swollen joints associated with asymmetric inflammation in one or more fingers or toes. A gout attack commonly affects the large toe and lasts for three to 10 days.
Over time, gout attacks can become more frequent, last longer, and may not resolve. This can lead to chronic gouty arthropathy, which can cause erosions and joint destruction.
Calcium pyrophosphate deposition disease (CPPD) or pseudogout (false gout) is a type of arthritis that can present similarly to gout or RA but is distinguishable from acute gout attacks.
Tests your healthcare provider may perform to differentiate between gout, CPPD, and RA include blood tests for uric acid, imaging tests, and synovial fluid analysis.
Reactive Arthritis
A painful form of inflammatory arthritis, reactive arthritis is caused by a bacterial infection of the genitals or bowels. It commonly affects the heels, toes, fingers, low back, knees, or ankles.
Previously known as Reiter’s syndrome, reactive arthritis is in the family of seronegative spondyloarthropathies. Symptoms generally appear within a month of a bout of diarrhea or a genital infection.
A blood test can identify bacterial infections, such as Chlamydia trachomatis, Campylobacter, Salmonella, Shigella, or Yersinia.
Bursitis
Bursitis is an inflammation of the small, fluid-filled sac (bursa) that acts as a cushion between a bone and other moving parts. Caused by overuse or injury, the condition causes joint pain and inflammation that can be mistaken for RA.
Bursitis typically affects only one joint at a time—commonly the knee, elbow, or shoulder—and does not have the systemic symptoms of RA.
Diagnosis is based on physical examination and imaging tests such as X-rays or MRIs. Your healthcare provider may sample fluid from the swollen area to rule out an infection as well.
Sarcoidosis
Sarcoidosis, an inflammatory disease that typically affects the lungs, skin, or lymph nodes, can mimic RA. Characterized by tiny, grain-like lumps (granulomas), sarcoidosis can manifest with synovitis in several joints and can be seropositive.
Like RA, sarcoidosis onset typically occurs between ages 30 and 50.
Other characteristics of sarcoidosis that help to distinguish it from RA include:
Cough Shortness of breath Weight loss Night sweats Fatigue
Sarcoidosis is formally diagnosed through biopsy.
Vasculitis
Vasculitis, inflammation of blood vessels caused by an autoimmune process, can affect joints and might mimic RA.
Two types of vasculitis, polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) can occur with symmetrical polyarthritis. In addition, people with vasculitis often test seropositive for rheumatoid factor.
A key difference is that vasculitis commonly presents with headaches. A detailed medical history can help distinguish PMR or GCA from RA. For example, a headache—along with shoulder and hip pain— may indicate vasculitis.
In some cases, a diagnosis of vasculitis may depend on observation of the disease over time, particularly if complications develop.
Dual Diagnosis
You may be so used to living with RA that you chalk up any change in your symptoms to the disease, rather than another possible cause.
If you are experiencing an unusual persistence of or increase in your RA symptoms, or if new ones are appearing, be sure to check in with your healthcare provider. Additional diagnoses can be considered and, at the very least, you can be evaluated to see if a modification of your RA treatment plan may be necessary.
While it’s possible that you could also have any of the common RA-mimics, the most common RA comorbidities—which may or may not have similar symptoms—are:
Cardiovascular disordersGastrointestinal diseaseRenal diseasesPulmonary diseasesInfectionsOsteoporosisTumorsDepression
A Word From Verywell
Joint pain, a common symptom of many conditions that can mimic rheumatoid arthritis, may complicate the diagnosis. If you aren’t improving with treatment, talk to your healthcare provider. You might need additional testing or a referral to a rheumatologist or other specialist.
As a patient living with joint pain, you are your best advocate. Ensuring an accurate diagnosis is essential for finding a treatment that works for you.
ChikungunyaHepatitis B and CHIVParvovirus B19Rubella
Viral arthritis usually goes away on its own after several weeks.
BursitisFibromyalgiaGoutLupusLyme diseaseSarcoidosisSclerodermaVasculitisViral infection
Osteoarthritis is a degenerative joint disease that causes the breakdown of cartilage that cushions joints. It is caused by wear and tear on the joints. OA commonly affects knees, hips, and hands. It is usually diagnosed after age 65.
