Rheumatoid Arthritis vs. Lupus: Differences and Similarities

Rheumatoid arthritis (RA) and lupus are both autoimmune diseases. RA is mainly limited to the joints, while lupus affects more than just the joints.

Rheumatoid arthritis (RA) and lupus are two varieties of autoimmune diseases. This means they are caused when the body’s immune system attacks its own tissue by mistaking it for a foreign body. 

Being autoimmune diseases, RA and lupus share a few similarities, but they also differ in many aspects. While RA attacks the immune system on the joints, lupus involves many other parts of the body besides the joints.

Like several other autoimmune diseases, both RA and lupus are more common in women than in men. Women are two to three times more likely to have RA than men. In the case of lupus, the odds are still higher, with women being up to nine times more likely to get lupus than men.

The symptoms of rheumatoid arthritis (RA) are mainly limited to the joints, particularly the small joints in the toes, fingers, hands, and feet. Although less common, RA may involve the wrists, elbows, knees, ankles, and other body parts. Joint involvement in RA is symmetric, which means that if the joints in the fingers of your left hand have pain, you will experience pain in the fingers of your right hand too. The common symptoms of RA are as follows:

• Warm, swollen, and painful joints
• Morning stiffness in the joints or stiffness after inactivity
• Joint deformity
• Fever
• Fatigue
• Loss of appetite
• Loss of weight
• Dryness in eyes
• Dry mouth
• Abnormal colored urine or no urine due to kidney impairment
• Numbness and tingling in the hands and feet
• Difficulty in breathing
• Pale skin
• Chest pain or pressure

The symptoms of RA do not remain the same all the time; they may exacerbate (flare-ups) and resolve (remissions) from time to time.

Lupus also shows remissions and flare-ups like RA. The symptoms of lupus, however, are not just restricted to the joints. Most patients with lupus experience fatigue (exhaustion) as their first complaint. Joint pain and fever may be the reason that many patients with lupus visit their doctor. Lupus symptoms include the following:

• Malar rash (butterfly-shaped rash involving the cheeks and bridge of the nose)
• Fever 
• Joint pain in the absence of joint deformity
• Sun sensitivity
• Pale or anemic look 
• Swelling 
• Dry and itchy eyes
• Dry mouth
• Fingers and joints turning pale or bluish on exposure to stress and cold
• Difficulty in breathing
• Chest pain
• Seizures 
• Increased tendency for bleeding
• Mental changes
• Cough
• Nausea and vomiting
• Abdominal pain
• Indigestion
• Weight loss
• Nerve pain
• Weakness
• Headache
• Memory impairment
• Frequent miscarriages

Rheumatoid arthritis (RA) and lupus share their symptoms with other diseases and need a thorough examination by your doctor for a diagnosis. 

Diagnosing rheumatoid arthritis

• History and physical examination: Your doctor will ask about your complaints in detail and other relevant information, such as a family history of any diseases or any medications you are on. Your doctor will examine you for any joint swelling, redness, warmth, and deformity. They may also check your muscle reflexes and examine whether other body parts show disease involvement.
• Blood tests: Your doctor may get your blood tested for various disease markers, such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and rheumatoid factor.
• Imaging tests: Your doctor may request imaging tests such as X-ray, ultrasound, and magnetic resonance imaging (MRI).

Diagnosing lupus

The diagnosis of lupus is quite difficult because the signs and symptoms of this disease are quite varied and may involve any part of the body.

• History and physical examination: Your doctor will ask about your complaints in detail and other relevant information, such as a family history of lupus, any other chronic conditions, and any medications you are on. They will examine you physically to look for the involvement of different body parts in the disease.
• Lab tests: Your doctor may recommend lab tests for various disease markers, such as blood counts, ESR, liver and kidney function tests, antinuclear antibody test (ANA), and urine analysis.
• Imaging: Your doctor may recommend imaging studies to determine how much your organs are affected by lupus. These include X-ray, MRI, and echocardiography.
• Biopsy: To determine the extent of kidney involvement, your doctor may take a small piece of the kidney tissue (biopsy) through a needle or small surgical cut and send it for lab examination. Biopsy of the skin may also be taken when lupus involves the skin.