The quick answer is yes, seronegative rheumatoid arthritis does exist. A seronegative test for rheumatoid arthritis means that a person tests negative for rheumatoid factor (RF) and cyclic citrullinated peptides (CCP). However, this answer requires some explanation and a little background. Rheumatoid arthritis (RA) is a condition characterized by swollen, painful joints. It’s different from osteoarthritis, the type of joint damage that occurs with aging.
RA occurs when your body’s immune system attacks the lining of your joints. Why this happens is complex. Anyone can get RA, but it’s most common in women at middle age.
There is no single test that confirms that you have RA. Diagnosis includes examination of the joints, possibly including X-rays, and blood tests. If your doctor suspects you might have RA, they’ll likely refer you to a specialist known as a rheumatologist.
One of the blood tests that can help to confirm RA is the rheumatoid factor (RF) test. RF is a protein (antibody) made by your immune system that binds a normal antibody that can cause tissue inflammation in your body. Elevated levels of RF typically occur with autoimmune diseases like RA and Sjogren’s syndrome and sometimes in the setting of infections, like hepatitis C and parvovirus.
However, RF testing doesn’t give a definite diagnosis. Healthy people with no autoimmune disorders may have high RF levels in their blood, particularly with advanced age. To further complicate the situation, people with RA can show normal levels of RF. Some people will test positive for a more recently discovered antibody directed against cyclic citrullinated peptides (CCP). CCP antibody, also known as anti-CCP, is more sensitive and specific and may appear before RF.
Someone with many of the symptoms of RA but normal RF/anti-CCP levels may not have RA at all. You may have another inflammatory autoimmune disease called spondyloarthritis. This is especially true if you have spine or sacroiliac joint involvement, or both.
The disorders of spondyloarthritis
Many of the disorders that fall under the heading of spondyloarthritis were once thought to be variants of RA. They include:
- psoriatic arthritis
- reactive arthritis
- ankylosing spondylitis
- enteropathic arthritis
- Whipple’s disease
- non-radiographic axial spondyloarthritis
Each of these disorders is unique, but they share a common root. They’re all inflammatory autoimmune disorders that cause arthritis in various parts of the body, particularly the spine.
These conditions may have arthritis in common, but there are some significant differences between RA and the class of diseases called spondyloarthritis. The first is that spondyloarthritis is more common in men, but under-diagnosed in women.
Secondly, most spondyloarthritis conditions include complications in addition to arthritis, such as:
- inflammatory bowel disease (IBD)
- inflammatory eye diseases
- aphthous ulcer
RA and the conditions of spondyloarthritis also differ in the way the arthritis is experienced. Arthritis in RA occurs in the same joints on both sides of the body. However, arthritis is experienced asymmetrically in spondyloarthritis and affects tendons (tenosynovitis).
In spondyloarthritis, inflammation often occurs in the feet and ankles. It can also flare up in the spine and in the places where tendons and ligaments attach to bones (enthesitis).
Unfortunately, like RA, spondyloarthritis disorders have no cure. However, symptoms can be managed and damage prevented through treatments such as:
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- disease-modifying antirheumatic drugs (DMARDs) and biologics
- topical creams for psoriasis
- steroid and NSAID drops for eye inflammation
- dietary changes for inflammatory bowel disorders (IBDs)
- Janus-kinase inhibitors (JAK inhibitors)
Talk to your doctor about the best options for treating your individual symptoms.