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Thromb Haemost 1995; 74(03): 900-903
DOI: 10.1055/s-0038-1649844
Original Article
Coagulation
Schattauer GmbH Stuttgart

The International and “NIH” Units for Thrombin - How Do They Compare?

Patrick J Gaffney
The National Institute for Biological Standards and Control, South Mimms, Potters Bar, Hertfordshire, UK
,
Tracey A Edgell
The National Institute for Biological Standards and Control, South Mimms, Potters Bar, Hertfordshire, UK
› Author Affiliations
Further Information

Publication History

Received 19 August 1994

Accepted after resubmission 27 April 1995

Publication Date:
09 July 2018 (online)

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Summary

The current International Standard (IS) for α-thrombin was established in 1991. It was related in unitage with the 1st IS for Thrombin established in 1975 and contains 100 IU of thrombin activity. The National Institute of Health (NIH) standard (Lot J) is in common use for the calibration of commercial thrombin reagents and this study reports on a comparison of the thrombin units defined by these 2 standards. This study has indicated that one “NIH” unit is equivalent to 1.1 to 1.3 IU of thrombin, depending on the influence of PEG in the assay. A unitage ratio figure of 1.15 was recommended following analysis of data obtained in the presence and absence of PEG in the comparative assays. This was confirmed by amidolytic assay data.

 

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