The effect of lupus anticoagulant in the second-generation assay for activated protein C resistance.

Abstract

The activated protein C resistance (APCR) assay is the test of choice to screen for factor V Leiden. We evaluated the effect of lupus anticoagulant on the baseline clotting time of the second-generation APCR assay with plasma samples from 54 patients to determine whether a falsely low APCR ratio could be predicted. We also assessed whether a modification of the assay could make it more reliable in the presence of strong lupus anticoagulants. Of 54 plasma samples, 5 yielded a false-positive APCR ratio, and all 5 had a prolonged baseline clotting time. Further dilution (1:40) of the plasma samples in factor V-deficient plasma led to correction of the APCR ratio and did not affect the sensitivity of the test for factor V Leiden. Our data support that the baseline clotting time is a good predictor of a false-positive APCR test result and should be checked before calculating the ratio. The modified APCR assay reliably identified the false-positive ratios and could be used to screen for factor V Leiden in samples with strong lupus anticoagulant.

• Authors: Brian D Ragland, Cari E Reed, Barbara M Eiland, Patricia H Tichenor, Christine L Hudson, George A Fritsma, Brian K Adler, Marisa B Marques
• Journal: American journal of clinical pathology (Am J Clin Pathol) Vol. 119 Issue 1 Pg. 66-71 (Jan 2003) ISSN: 0002-9173 [Print] England
• PMID: 12520699 (Publication Type: Evaluation Study, Journal Article)

Chemical References

• Lupus Coagulation Inhibitor
• Reagent Kits, Diagnostic
• factor V Leiden
• Factor V

Topics

• Activated Protein C Resistance (blood, diagnosis)
• Adult
• Blood Coagulation Tests (methods)
• Factor V (analysis)
• False Positive Reactions
• Female
• Humans
• Lupus Coagulation Inhibitor (blood, physiology)
• Mass Screening (methods)
• Predictive Value of Tests
• Reagent Kits, Diagnostic
• Reproducibility of Results
• Sensitivity and Specificity