Interpretation of Mutated Citrullinated Vimentin (MCV) Antibody Results
A Mutated Citrullinated Vimentin (MCV) antibody result of <20 U/mL is completely normal and does not indicate a borderline high value.
Understanding MCV and CCP Antibody Test Results
MCV and CCP antibodies are both important serological markers used in the diagnosis of rheumatoid arthritis (RA). Here's how to interpret these results:
- MCV antibody result <20 U/mL: This is clearly within the normal reference range and is considered negative
- CCP antibody result <16 U/mL: This is also negative (reference range for negative is <20 U/mL)
Reference Ranges and Interpretation
Serological tests for autoimmune conditions typically establish clear cutoff values:
- Values below the cutoff are considered negative
- Values above the cutoff are considered positive
- There is no "borderline high" category for values that are clearly below the cutoff
Diagnostic Accuracy of Antibody Tests
The diagnostic value of these antibodies has been well-studied:
- Anti-MCV antibodies at a cutoff point of >1.2 mol/L have shown 76% sensitivity and 100% specificity for diagnosing RA 1
- For early RA diagnosis, anti-MCV has demonstrated 70% sensitivity and 100% specificity 2
- Anti-CCP antibodies generally show high specificity (90-99%) for RA diagnosis 3
Clinical Implications
When both MCV and CCP antibody tests are negative (as in this case):
- These results strongly suggest the absence of rheumatoid arthritis
- The likelihood of developing RA in the future is significantly reduced
- Other diagnoses should be considered if joint symptoms are present
Common Pitfalls in Interpretation
Misinterpreting normal values as borderline: A value that is clearly below the established cutoff (like <20 U/mL for MCV) is not borderline high - it is definitively negative
Assuming that being "close to" the cutoff is significant: Laboratory reference ranges are established to provide clear distinctions between positive and negative results
Overinterpreting slight variations within the normal range: Values within the normal range have minimal clinical significance regardless of where they fall within that range
Conclusion
Both the MCV antibody result (<20 U/mL) and CCP antibody result (<16 U/mL) are negative and do not indicate borderline high values. These results should be interpreted as normal and not suggestive of rheumatoid arthritis or other autoimmune conditions that produce these antibodies.