College of American Pathologists
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  Shorts on Standards


CAP Today




February 2013

The CAP has 30 official liaisons to various organizations who attend scientific meetings or designate others to do so. They report to the Standards Committee, which reports to the Council on Scientific Affairs. We publish periodically bits of what the CAP’s outbound liaisons hear and see in their liaison roles.

New lot of secondary reference material

Dorothy M. (Adcock) Funk, MD
Elizabeth M. Van Cott, MD

Results of coagulation studies can have significant impact on patient care. In many circumstances, they provide the diagnosis. But how do you know if a coagulation test result is accurate? Also, when following consensus guidelines for either diagnosis or treatment of a bleeding disorder, how do you know that the results in your laboratory agree with the methods used to establish the guidelines?

To help determine these answers, the CAP Coagulation Resource Committee works with the International Society on Thrombosis and Haemostasis (ISTH), which held its annual Scientific Standardization Committee meeting in July 2012 in Liverpool, UK. There is no primary (pure substance) reference material. The ISTH formed the Coagulation Standards Working Group in 1993 to develop and oversee the production and distribution of a commutable secondary reference material for a variety of coagulation tests—namely factors II, V, VII, VIII, IX, X, XI, and XIII; vWF (including the propeptide); protein C; protein S; antithrombin; and fibrinogen. This secondary standard is calibrated against WHO International Standards by multiple expert laboratories. The National Institute for Biological Standards and Control in the UK is responsible for storage, labeling, and distribution.

Manufacturers may use this material to develop calibrators for their assay kits. The CAP Coagulation Resource Committee also uses the secondary reference material in its proficiency testing programs. At the 2012 ISTH meeting, the CAP liaison presented the results obtained from more than 100 laboratories for the third lot. Method-specific bias was low (<10 percent) for most analytes evaluated in the CAP Surveys (specifically vWF antigen and ristocetin cofactor, antithrombin activity and antigen, protein C antigen, and free protein S antigen). Protein C and protein S activity assays demonstrated 10 to 20 percent bias from the assigned values, and none of the assays demonstrated greater than 20 percent bias.

At the recent annual meeting, the ISTH Scientific Standardization Committee voted to accept the new lot, manufactured by a company in Vienna, Austria. This new lot (No. 4) has recently been made available and will be used in future CAP Surveys.

Dr. (Adcock) Funk, medical director of Esoterix, is the CAP liaison to ISTH and a member of the CAP Coagulation Resource Committee. Dr. Van Cott, director of the Coagulation Laboratory at Massachusetts General Hospital, is a member of the CAP Standards Committee. For more information on the SSC/ISTH meeting, visit the Web site The authors thank Anthony Hubbard for historical information about the ISTH Coagulation Standards Working Group.