Autoimmune serology
Anti-CCP (ACPA)
Highly specific for rheumatoid arthritis; predicts erosive disease.
Sample
Serum
Clinical reference range
— to 20 U/mL
Negative
Conv: —–20 U/mL
Biology
What it measures
IgG against citrullinated peptides (PAD-mediated post-translational modification).
Clinical use
Why we order it
RA diagnosis (ACR/EULAR 2010 criteria) and prognosis. Specificity ~95%.
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