Description
Why It’s Done (Purpose):
1. Diagnose Autoimmune Disorders:
o Most commonly used to support the diagnosis of ankylosing spondylitis (AS) and other spondyloarthropathies, including:
Reactive arthritis
Psoriatic arthritis (axial type)
Juvenile idiopathic arthritis (enthesitis-related type)
Inflammatory bowel disease–related arthritis
2. Assess Genetic Predisposition:
o A positive result indicates a genetic predisposition but not a diagnosis on its own.
o 90–95% of patients with ankylosing spondylitis are HLA-B27 positive, but many people with HLA-B27 never develop disease.
3. Support Differential Diagnosis:
o Helps differentiate inflammatory back pain from other causes (e.g., mechanical back pain or degenerative diseases).
Preparation Guidelines:
• No special preparation is required.
• A blood sample is drawn from a vein.
• Inform your healthcare provider of:
o Any current infections or autoimmune symptoms.
o Recent blood transfusions, as they may affect test accuracy.
