Differences Between Rheumatoid Arthritis and Lupus

Rheumatoid arthritis (RA) and lupus are both autoimmune diseases that attack your body in a similar fashion. In autoimmune diseases, your immune system is unable to distinguish between certain healthy tissues and dangerous pathogens, like viruses or bacteria. It begins to attack, creating autoantibodies that damage your organs and tissues.

The specific parts of the body the immune system attacks are determined by what disease you have. While RA and lupus are similar, their differences are important when it comes to how you're diagnosed and treated.

RA and Lupus Basics

Rheumatoid arthritis occurs when your immune system attacks the lining of your joints and, in severe cases, your internal organs. RA can also affect your eyes, lungs, and skin.

Some people with RA have flares (when symptoms are more severe) and remissions (when symptoms are less severe). For others, the symptom severity is more consistent.

In most cases of RA, tests identify proteins called rheumatoid factors in the blood. People positive for rheumatoid factors have seropositive RA. People without them have seronegative RA.

Lupus refers to several different inflammatory conditions involving the skin and/or internal organs. The systemic form, called systemic lupus erythematosus (SLE), is a disease that comes in flares and remissions, with your immune system attacking different tissues and organs. It can affect any part of the body but most commonly attacks your skin, joints, heart, lungs, blood, kidneys, and brain.

Several types of lupus exist:

• Systemic lupus erythematosus (SLE), the most common type
• Drug-induced lupus 
• Chronic cutaneous (discoid) lupus 
• Neonatal lupus

Causes

Researchers aren't sure what causes RA, but they suspect several factors contribute to its development, including:

• Genetics
• Environment
• Hormones 

Likewise, the exact cause of lupus isn't yet known. Factors that may impact the development of this disease include:

• Genetics
• Hormones
• Environmental factors
• Certain infections
• Medication

In cases of drug-induced lupus, symptoms usually go away after the medication that caused it is discontinued. 

Who Gets It?

RA and lupus both are more common in women than in men.

RA can begin at any time in life, including childhood, but onset typically occurs between ages 35 and 50. It's more common in certain Native American communities than in people of European descent.

Lupus is more commonly diagnosed in younger people between the ages of 15 and 44. People of color develop it more often than white people. 

Symptoms

Rheumatoid arthritis and lupus share some general symptoms, but each has many the other doesn't, which can help you (and your healthcare provider) tell them apart.

Symptoms they have in common include:

• Joint pain
• Joint stiffness
• Swelling and inflammation
• Fatigue
• Low-grade fever

Symptoms of RA that aren't typical of lupus are:

• Redness or warmth near swollen joints
• Rheumatoid nodules
• Hand and foot deformities
• Joint subluxations (partial dislocations) or dislocations

Symptoms of lupus that aren't typical of RA include:

• Unexplained rashes that may become sores or lesions
• Butterfly-shaped rash across the cheeks
• Anemia
• Hair loss
• Pain in the chest with deep breathing (pleurisy)
• Sensitivity to sunlight or other forms of light (photosensitivity)
• Abnormal blood clotting
• Unexplained weight change
• Raynaud's disease (extremely cold hands that turn blue or white and are hard to warm up)

Diagnosis

Autoimmune diseases are notoriously hard to diagnose. It takes several steps to figure out whether you have an autoimmune disease, and, if so, which one. Getting the diagnosis right is key to effective treatment, so it's worth the time and effort it takes to get to the bottom of things.

Whatever diagnosis you end up with, the process will likely start with a detailed description of your symptoms, family medical history, and a physical exam. From there, the healthcare provider will decide what tests and imaging to order.

Labs and Tests

Because RA and lupus are both inflammatory, several tests that measure inflammatory markers in your blood are common parts of both diagnoses. The results simply tell the practitioner whether you do or don't have significant inflammation. These tests include:

• Complete blood count (CBC)
• Erythrocyte sedimentation rate (ESR or sed rate)
• C-reactive protein (CRP)

Other tests look for specific antibodies in your blood. You may have any combination of these tests, depending on what your healthcare provider suspects at this point in the process:

• Anti-cyclic citrullination peptide (anti-CCP): This autoantibody is found in high levels almost exclusively in people with RA and is present in between 60% and 80% of these individuals.
• Rheumatoid factor (RF): This antibody is found in about 70% to 80% of people with RA, but also occurs in other autoimmune conditions and infections.
• Antinuclear antibody (ANA): This test is positive in almost all people with lupus (SLE), so it’s helpful in ruling out the condition. However, people with other medical conditions, and even healthy people, can have a positive ANA test.

Your healthcare provider may order a number of other antibody tests, as well. And if you're suspected of having lupus, a urinalysis and a tissue biopsy may be performed to gauge organ involvement.

Imaging

Imaging tests that may be part of the diagnostic process for both conditions include:

• X-rays
• Magnetic resonance imaging (MRI)
• Ultrasound

Again, additional imaging may be done to look for organ involvement in lupus, such as:

• Echocardiogram to look at the heart
• Computed tomography (CT) scan of the chest or abdomen to look at other internal organs.

Because these diseases are so hard to diagnose, you may have any of these tests and even more before you receive a firm diagnosis.

Treatment

Neither RA nor lupus can be cured. The goals of treatment are to minimize symptoms and prevent damage, with long-term remission being the best-case scenario.

Both of these conditions are typically treated by rheumatologists—healthcare providers who specialize in musculoskeletal diseases and certain autoimmune conditions. 

Drugs

Classes of medications that may be used to treat both RA and lupus include:

• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Immunosuppressants/disease-modifying anti-rheumatic drugs (DMARDs)
• Corticosteroids
• Biologics and biosimilars

Other Non-Surgical Treatments

Other treatment approaches can be similar for both conditions, such as:

• Physical therapy or occupational therapy
• Steroid injections
• Massage therapy
• Acupuncture
• Stress management
• Dietary changes
• Other lifestyle changes

Surgery

Surgery may become necessary in severe cases of either disease, but such procedures are considered last-resort treatment options.

With RA, you may need a joint replacement, depending on which joints are affected and to what degree. Knee and hip replacements are the most common types.

Joint replacement is less common in lupus. It may become necessary due to damage from the disease itself or from some of the drugs used to treat it. As with RA, the hips and knees are the most frequently replaced joints.

Some people with lupus nephritis may eventually need dialysis or a kidney transplant.