Bovine plasma as a reference standard for the factor VIII assay.

Area of Science:

• Hematology
• Biochemistry
• Clinical Diagnostics

Background:

• The definition of a unit of factor VIII procoagulant activity lacks precision due to variations in normal plasma levels and factor VIII lability.
• Existing methods for preparing factor VIII standards are hampered by activity loss during pooling and instability, particularly at low temperatures.
• Lyophilized standards can exhibit variable activity due to dissolution challenges.

Purpose of the Study:

• To develop a stable and reliable standard for factor VIII procoagulant activity.
• To address the imprecision in current factor VIII unit definitions.
• To provide a standard applicable to both one-stage and two-stage factor VIII assays.

Main Methods:

• Preparation of a working standard using beef plasma diluted in outdated human blood bank plasma.
• Ensuring stability of the prepared standard at -20°C for extended periods.
• Verification of the working standard's activity level through repeated assays against lyophilized national standards and small pools of normal donor plasma.

Main Results:

• The developed standard demonstrates stability at -20°C for years.
• The activity of the working standard was consistently verified against established references.
• The standard proved effective for both one-stage and two-stage factor VIII assays.

Conclusions:

• A stable and reliable standard for factor VIII procoagulant activity has been successfully prepared.
• This new standard addresses the limitations of existing methods, enhancing precision in factor VIII measurement.
• The developed standard is suitable for routine use in clinical laboratories, improving diagnostic accuracy.