Determination of APTT factor sensitivity--the misguiding guideline.

Area of Science:

• Hematology
• Clinical Chemistry
• Coagulation Diagnostics

Background:

• The Clinical and Laboratory Standards Institute (CLSI) provides guidelines for assessing activated partial thromboplastin time (APTT) reagent sensitivity to clotting factor deficiencies.
• This involves mixing normal and deficient plasmas to evaluate reagent performance.

Purpose of the Study:

• To determine the factor sensitivity of two APTT reagents, Actin FS and Actin FSL, using the CLSI guideline.
• To assess the reliability and consistency of APTT reagents in detecting clotting factor deficiencies.

Main Methods:

• Activated partial thromboplastin time (APTT) assays were performed on a Sysmex CS-5100 analyzer using Actin FS and Actin FSL reagents.
• Quality of commercial factor-deficient and reference plasmas was evaluated through clotting factor assays and thrombin generation tests (TGT).

Main Results:

• Normal ranges for Actin FS and Actin FSL were established from 50 healthy subjects.
• APTT sensitivity to factor deficiencies varied significantly based on the source of deficient plasma.
• Thrombin generation potential was not solely correlated with specific clotting factor levels in deficient plasmas.

Conclusions:

• Following the CLSI guideline for determining APTT factor sensitivity can yield inconsistent and potentially misleading results.
• The study highlights variability in APTT reagent performance and the complexity of coagulation factor interactions.