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Updated: May 6, 2026
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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
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Quantifying Lupus Anticoagulant Interference in Intrinsic Coagulation Factor Activity Assays and Evaluating the
Yu Yang1, Yuanyuan Li1, Anna Jiang1
1Department of Clinical Laboratory, Peking University First Hospital, Beijing, China.
Summary
Lupus anticoagulant (LA) can falsely lower coagulation factor levels. A new SCT correction assay effectively mitigates this interference, improving accuracy for patients with antiphospholipid syndrome or lupus.
Area of Science:
- Hematology
- Clinical Chemistry
- Immunology
Background:
- Lupus anticoagulant (LA) interferes with coagulation tests.
- LA can falsely reduce intrinsic coagulation factor activities.
- Quantitative relationship between LA intensity and assay interference is unclear.
Purpose of the Study:
- To investigate the quantitative relationship between LA intensity and interference in coagulation factor assays.
- To evaluate the efficacy of a modified assay using SCT-confirm reagent for LA interference reduction.
Main Methods:
- Studied 100 LA-positive patients with antiphospholipid syndrome or SLE.
- Measured FVIII:C, FIX:C, and FXI:C using one-stage and modified SCT-confirm assays.
- Calculated pseudo-lowering degree (PLD) to quantify correction efficacy.
Main Results:
- Reduced FVIII:C, FIX:C, and FXI:C observed in 27%, 23%, and 26% of patients, respectively.
- LA intensity associated with decreased FIX:C and FXI:C, but not FVIII:C.
- SCT assay corrected factor levels in 66.7% (FVIII:C), 82.6% (FIX:C), and 92.3% (FXI:C) of affected cases.
Conclusions:
- FVIII:C, FIX:C, and FXI:C show differential susceptibility to LA interference.
- SCT-based correction effectively mitigates LA interference, particularly for FXI.
- This approach avoids misclassification of factor deficiencies in LA-positive patients.
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