A collaborative study to establish the 2nd International Standard for Antithrombin Concentrate

Area of Science:

• Biochemistry
• Clinical Chemistry
• Pharmacology

Background:

• The 1st International Standard for Antithrombin Concentrate (88/548) required calibration of a replacement.
• Accurate standardization is crucial for reliable antithrombin activity measurements in clinical diagnostics and research.

Purpose of the Study:

• To calibrate and establish a replacement for the 1st International Standard for Antithrombin Concentrate.
• To validate the candidate concentrate (96/520) through a collaborative study involving multiple laboratories.

Main Methods:

• Eighteen laboratories participated in a collaborative study.
• Candidate concentrate (96/520) was assayed against the 1st International Standard (88/548) using functional and antigenic assays.
• Inter-laboratory agreement was assessed using mean % gcv (general coefficient of variation).

Main Results:

• Excellent agreement between laboratories was observed, with mean % gcv of 3.3 for functional and 5.9 for antigenic assays.
• The functional potency of the candidate concentrate was found to be 7.9% lower than its antigenic potency (p<0.05).
• The candidate concentrate (96/520) was established as the 2nd International Standard for Antithrombin Concentrate.

Conclusions:

• The candidate concentrate (96/520) demonstrated high consistency across laboratories for both functional and antigenic assays.
• The 2nd International Standard for Antithrombin Concentrate (96/520) was established with labelled potencies of 4.7 IU/ampoule (functional) and 5.1 IU/ampoule (antigenic).
• This new standard will facilitate accurate and reproducible antithrombin activity quantification worldwide.