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Updated: Sep 29, 2026
Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
In vitro detection of mild inhibitors to factor VIII in hemophilia
Abstract:
Plasma samples from patients with severe classic hemophilia, suspected of having mild inhibitors not detected in the standard Bethesda inhibitor test, were examined in modified Bethesda tests and in a screening test based on the activated partial thromboplastin time (APTT). The APTT test was more sensitive to mild inhibitors than any modification of the Bethesda method. Increasing the ratio of patient to normal plasma in either the APTT or the Bethesda test improved the sensitivity to mild inhibitors. If a patient's plasma is used as its own control in the APTT test, results are more consistent as minor fluctuations in the APTT occur over time.
Insights
The activated partial thromboplastin time (APTT) test is more sensitive for detecting mild inhibitors in severe classic hemophilia patients than the Bethesda method. Optimizing plasma ratios and using patient plasma as a control enhances inhibitor detection accuracy.
Area of Science:
- Hematology
- Clinical Chemistry
Background:
- Severe classic hemophilia poses challenges in inhibitor detection.
- Standard Bethesda inhibitor tests may miss mild inhibitors.
Purpose of the Study:
- To evaluate the sensitivity of the activated partial thromboplastin time (APTT) test for detecting mild inhibitors in hemophilia.
- To compare APTT test performance against modified Bethesda methods.
Main Methods:
- Plasma samples from severe classic hemophilia patients were analyzed.
- Modified Bethesda tests and an APTT-based screening test were employed.
- Patient to normal plasma ratios were varied to assess sensitivity.
Main Results:
- The APTT test demonstrated higher sensitivity to mild inhibitors compared to Bethesda method modifications.
- Increasing the patient to normal plasma ratio improved sensitivity in both APTT and Bethesda tests.
- Using patient plasma as its own control in the APTT test yielded more consistent results.
Conclusions:
- The APTT test is a more sensitive screening tool for mild inhibitors in hemophilia.
- Adjusting plasma ratios and using patient-specific controls can improve inhibitor detection.
- Enhanced sensitivity aids in managing hemophilia patients with potential low-titer inhibitors.
