Which laboratory test is commonly used in the evaluation of suspected ankylosing spondylitis?

Which laboratory test is commonly used in the evaluation of suspected ankylosing spondylitis?

• A. WBC count
• B. ESR
• C. CRP
• D. ANA

Answer: (B)

Inflammation in ankylosing spondylitis drives changes in blood tests that reflect the body's inflammatory burden. Erythrocyte sedimentation rate rises with systemic inflammation and is a traditional, readily available marker used when AS is suspected to gauge overall inflammatory activity and to follow changes over time. While C-reactive protein can also be elevated and may respond quickly to shifts in inflammation, the ESR has long been a standard initial inflammatory marker in rheumatology and is commonly ordered early in the evaluation. A normal white blood cell count is not specific to AS and isn’t useful for diagnosing this condition. ANA is more relevant to other autoimmune diseases and isn’t helpful for ankylosing spondylitis.

Inflammation in ankylosing spondylitis drives changes in blood tests that reflect the body's inflammatory burden. Erythrocyte sedimentation rate rises with systemic inflammation and is a traditional, readily available marker used when AS is suspected to gauge overall inflammatory activity and to follow changes over time. While C-reactive protein can also be elevated and may respond quickly to shifts in inflammation, the ESR has long been a standard initial inflammatory marker in rheumatology and is commonly ordered early in the evaluation. A normal white blood cell count is not specific to AS and isn’t useful for diagnosing this condition. ANA is more relevant to other autoimmune diseases and isn’t helpful for ankylosing spondylitis.