Diagnosis and Testing
How is ankylosing spondylitis diagnosed?
The diagnosis of ankylosing spondylitis (AS) depends on a number of factors including signs and symptoms, physical examination, family history, laboratory tests, imaging studies that include x-ray and MRI to confirm the involvement of the joints in the hip (sacroiliac joint). Due to the wide-range of symptoms, which can occur from patient to patient, a doctor must make the diagnosis-typically a rheumatologist. Genetics plays an important role in ankylosing spondylitis (AS). Greater than 90% of patients with AS have an important marker, called HLA-B27, on their white blood cells. Your doctor may order blood test to check for inflammation markers and the presence of the HLA-B27 gene. But note that only ~20% of those with the specific HLA-B27 gene will experience inflammatory conditions like AS. In order to diagnose AS, you doctor - typically a rheumatologist - will take into account the physical exam including X-rays, family history of AS, and the presence of the HLA-B27 gene. X-rays are used to confirm the involvement of the joints in the hip (sacroiliac joint).