ISTH Members Invited to Participate in International Collaborative Study to Calibrate WHO Standards
Wednesday, September 23, 2015
Posted by: Luke Blount
Craig Thelwell and Colin Longstaff of the National Institute for Biological Standards and Controls (NIBSC) issued the following invitation to ISTH members:
Invitation to participate in an international collaborative study to calibrate WHO Standards for Ancrod and Batroxobin
Stocks of the WHO 1st International Reference Reagent (IRR) for Ancrod (74/581) and the 2nd British Standard for Batroxobin (93/526) are both nearly exhausted and will be replaced with new WHO standards. Ancrod and Batroxobin are both ‘thrombin-like enzymes’ and we are proposing to organize a joint collaborative study to calibrate both replacement standards. We are therefore looking to recruit laboratories with appropriate experience to participate in the calibration exercise.
The assays we are interested in will involve clotting fibrinogen or plasma. If you have an established method in your laboratory that can measure clotting times, and would be interested in taking part, we would like to hear from you. Briefly, we will provide existing standards for Ancrod and Batroxobin and candidate replacements for each one. It will be necessary to perform 4 simple clotting assays and report clotting times over a dilution range of standard and test preparations.
We will be happy for laboratories to perform in-house assays (we will advise on dilution ranges and replication) or we can supply our methods. The methods we can provide will be:
- An automated coagulometer method (in our case the Werfen, ACL Top 500)
- A manual coagulometer method
- A simple microtitre plate-based method following fibrinogen clotting by absorbance in a plate reader.
It will not be necessary to complete any detailed analysis- raw data for clotting times will be returned to NIBSC for statistical analysis on completion of the assays. Data collection for the collaborative study is scheduled for Q4 2015, to be completed by early 2016. You will receive a report of the study findings and be asked for your opinions before the report is submitted to the ISTH/SSC and then to WHO in the summer of 2016.
Once the standards have been established by WHO, we will be able to provide some free ampoules as a thank you. If you are interested in participating, or would like more information please contact either of us at
Many thanks in advance for your consideration of this project, please contact us by end October 2015 at the latest.