Arthritis describes inflammation and stiffness in the joints. Seronegative arthritis is a specific category of inflammatory joint conditions. This classification is based on the absence of certain autoantibodies in the blood, which are typically present in other forms of inflammatory arthritis. Seronegative arthritis is a chronic condition.
Defining Seronegative Arthritis
“Seronegative” arthritis refers to the absence of specific autoantibodies in blood tests. These antibodies are primarily rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies. Their absence distinguishes seronegative arthritis from “seropositive” arthritis, like rheumatoid arthritis, where these antibodies are detectable.
The term seronegative highlights a diagnostic characteristic, not a less severe form of the disease. While RF and anti-CCP antibodies are absent, other inflammatory markers, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), may still be elevated. Some individuals initially diagnosed as seronegative may later test positive for these antibodies, leading to a reclassification.
Key Types of Seronegative Arthritis
Seronegative arthritis encompasses a group of conditions often referred to as seronegative spondyloarthropathies.
Ankylosing Spondylitis (AS) primarily affects the spine and sacroiliac joints. It leads to pain and stiffness, and in advanced cases, can cause new bone formation that fuses sections of the spine.
Psoriatic Arthritis (PsA) affects some people with psoriasis, a skin condition characterized by red patches with silvery scales. PsA can involve various joints, the skin, and nails.
Reactive Arthritis is triggered by an infection in another part of the body, most commonly the intestines, genitals, or urinary tract. It causes joint pain and swelling, often in the knees, ankles, and feet.
Enteropathic Arthritis is associated with inflammatory bowel diseases (IBD) like Crohn’s disease and ulcerative colitis. This type of arthritis can cause joint inflammation and tenderness in various joints, sometimes alongside digestive symptoms.
Common Symptoms
Individuals with seronegative arthritis experience a range of symptoms. Inflammatory back pain is common, often worsening with rest and improving with activity, and noticeable in the morning.
Sacroiliitis, inflammation of the sacroiliac joints, is frequently observed. Enthesitis, inflammation where tendons or ligaments attach to bone, often affects areas like the heels or sole of the foot. Dactylitis, characterized by “sausage-like” swelling of an entire finger or toe, is also a distinct feature.
Peripheral joint involvement, affecting joints in the hands, feet, and shoulders, can lead to pain, swelling, and stiffness. Extra-articular (outside the joint) symptoms can also occur. These may include eye inflammation (uveitis), skin issues (such as psoriasis in PsA), or bowel inflammation in enteropathic arthritis.
Diagnosis Process
Diagnosing seronegative arthritis can be challenging due to the absence of specific blood markers like RF and anti-CCP antibodies. The diagnostic process relies on a thorough clinical evaluation, including patient history and a physical examination of affected joints.
Imaging studies play a role in diagnosis. X-rays and MRI scans, particularly of the sacroiliac joints, can reveal inflammation or structural changes. Genetic testing, such as for the HLA-B27 gene, may also be performed, as its presence is associated with some types of seronegative arthritis. Diagnosis often involves a process of exclusion, ruling out other conditions with similar symptoms.
Treatment Approaches
Treatment for seronegative arthritis aims to reduce inflammation, manage pain, preserve joint function, and prevent disease progression. Pharmacological interventions often begin with non-steroidal anti-inflammatory drugs (NSAIDs) to alleviate pain and inflammation. If NSAIDs are insufficient, conventional disease-modifying antirheumatic drugs (DMARDs), such as sulfasalazine or methotrexate, may be prescribed.
Biologic therapies, particularly TNF inhibitors, are used for more severe cases, targeting specific inflammatory pathways. These medications help control the immune response that drives the disease. Non-pharmacological approaches are also important. Physical therapy helps maintain mobility and flexibility, while regular exercise can strengthen muscles and reduce stiffness. Lifestyle modifications, including a balanced diet and smoking cessation, contribute to disease management.