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Monday, February 16, 2015

Diagnosing Ankylosing Spondylitis

Ankylosing Spondylitis (AS) can take a long time to develop. The symptoms are the same or similar to generic back pain and other autoimmune diseases. So for a diagnosis the Rheumatologist needs to distinguish it from other possibilities by looking for specific AS only characteristics.

Along with showing general symptoms of AS, these characteristics below, combined, are generally used in diagnosis:

  • Grade 2 bilateral sacroiliitis OR, Grade 3 or higher unilateral sacroiliitis via Xray - in layman's term this means the signs of damage caused by inflammation of sacral joints (sacroiliitis) seen in both of the sacral joints, OR a definite vision of damage or complete fusion, seen in at least one sacral joint.
  • HLA-B27 gene or family history of AS - 80-95% of people with AS have the HLA-B27 gene. Note having the HLA-B27 gene doesn't meant you will have or get AS. Only 9% of the population have this gene, and only 5% of those develop AS. You can have AS without this gene, or any previous history.
  • High levels of C-reactive protein (CRP) and raised erythrocyte sedimentation rates (ESR) - determined by a blood test, these levels indicate inflammation. Not everyone who has AS actually show high levels of inflammation in their blood. This is only seen in 50-70% of people with AS.

If you have any suspicions that you may have AS, please speak to your General Practitioner to get a referral to a Rheumatologist to run the necessary tests.


A description of the sacroiliitis gradings can be found here: http://radiopaedia.org/articles/sacroiliitis-grading