Lab tests for Ankylosing Spondylitis Diagnosis

The main blood test for ankylosing spondylitis is one to check for the HLA-B27 gene, which is present in the majority of Caucasians with ankylosing spondylitis. However, this test also has limitations. The gene is found in much lower percentages of African Americans with ankylosing spondylitis, and in ankylosing spondylitis patients from some Mediterranean countries. Also, the gene is found in many people who do not have ankylosing spondylitis, and will never get it. Still, when the gene is found in people who have symptoms of ankylosing spondylitis and/or x-ray evidence of ankylosing spondylitis, this finding helps support the ankylosing spondylitis diagnosis.

It is important to note that the HLA-B27 test is not a diagnostic test for ankylosing spondylitis.

Since there is no single blood test for AS, laboratory work may, or may not, be of help. Elevated erythrocyte sedimentation rate (ESR), also known as SED rate, and C-reactive protein (CRP) are common indicators of inflammation. Elevated levels of these markers, however, are not present in all AS patients and, when they are, it can be from other causes such as anemia, infection, or cancer. For example, it is estimated that less than 70 percent of people with AS have a raised ESR level.

Finally, there is no association between AS and rheumatoid factor (associated with rheumatoid arthritis) and antinuclear antibodies (associated with lupus.)

Urinalysis is often done to look for accompanying abnormalities of the kidney as well as to exclude kidney conditions that may produce back pain that mimics ankylosing spondylitis.



Symptoms evaluation for Ankylosing Spondylitis Diagnosis

Physical Exam for Ankylosing Spondylitis Diagnosis

Medical History for Ankylosing Spondylitis Diagnosis

Imaging tests for Ankylosing Spondylitis Diagnosis



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