Which laboratory tests are commonly evaluated when Ankylosing Spondylitis is suspected?

• A. ANA and RF
• B. ESR and HLA-B27
• C. CBC and ESR
• D. CRP and RF

Answer: (B)

When ankylosing spondylitis is suspected, you look for signs of inflammation and a genetic predisposition. The erythrocyte sedimentation rate is a non-specific marker that rises with inflammation and often helps indicate disease activity in AS. The HLA-B27 genetic marker is strongly associated with AS; its presence makes the diagnosis more likely in the right clinical context, though it’s not definitive on its own. Together, these two tests best reflect what clinicians monitor and assess early in suspected AS. RF and ANA are usually negative in AS, helping differentiate it from rheumatoid arthritis or lupus, and CBC is a broad, non-specific test.