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Anti-CCP Antibody Unit Converter
Anti-CCP (Anti-Cyclic Citrullinated Peptide), also known as ACPA (Anti-Citrullinated Protein Antibodies), constitutes a group of autoantibodies directed against peptides where the amino acid arginine has been converted to citrulline. This post-translational modification is a key trigger in the pathophysiology of Rheumatoid Arthritis (RA).
Clinically, Anti-CCP is the most specific serological marker for Rheumatoid Arthritis (specificity >95%), distinguishing it from other autoimmune conditions more effectively than Rheumatoid Factor (RF). High titers are strongly associated with aggressive, erosive joint disease and poor radiographic prognosis. Because these are antibodies, results are reported in International Units (U/mL) or Arbitrary Units (AU/mL) standardized against WHO reference materials, rather than mass units. This converter handles the interchange between standard clinical units and SI prefix variations.
SI Units
RecommendedKilo-units per liter (Numerically equal to U/mL).
Conventional Units
Clinical Context
Anti-CCP interpretation typically uses a cut-off established by the specific assay manufacturer (often 20 U/mL). Values > 3 times the upper limit of normal (e.g., > 60 U/mL) are considered “High Positive” and have a very high positive predictive value for RA.
Anti-CCP can be detected years before the onset of clinical symptoms. It is included in the 2010 ACR/EULAR classification criteria for Rheumatoid Arthritis. Unlike acute phase reactants (CRP), Anti-CCP levels tend to remain stable over time, although very high levels correlate with radiographic progression.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., U/mL). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like kU/L) are instantly updated.
Verify Units
Check the SI Units section. Note that U/mL and kU/L are numerically identical.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
Anti-CCP is a heterogeneous mixture of antibodies. We measure biological activity/binding, not specific mass. Therefore, arbitrary “Units” are used.
In this calculator, they are treated as 1:1 for convenience, but in clinical practice, “Arbitrary Units” (AU) depend strictly on the specific manufacturer’s kit.