An International Standard for Low Molecular Weight Heparin

T W Barrowcliffe; A D Curtis; E A Johnson; D P Thomas

doi:10.1055/s-0038-1647623

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 1988; 60(01): 001-007
DOI: 10.1055/s-0038-1647623

Original Article

Schattauer GmbH Stuttgart

An International Standard for Low Molecular Weight Heparin

Authors

T W Barrowcliffe

The National Institute for Biological Standards and Control, South Mimms, Herts., UK
A D Curtis

The National Institute for Biological Standards and Control, South Mimms, Herts., UK
E A Johnson

The National Institute for Biological Standards and Control, South Mimms, Herts., UK
D P Thomas

The National Institute for Biological Standards and Control, South Mimms, Herts., UK

Abstract

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Summary

An international collaborative study has been carried out with the aim of establishing an international standard for low molecular weight (LMW) heparin. Three preparations of LMW heparin were assayed against the International Standard for unfractionated heparin (UFH) by 25 laboratories in 13 countries, using nine different assay methods. The results confirmed previous findings of non-parallel assays, wide interlaboratory variability and differences between methods when LMW heparins are assayed against a UFH standard. Use of one of the LMW heparins as a standard for the other two gave parallel assays and much closer agreement between laboratories. The preparation in ampoules coded 85/600 was selected as likely to give the best agreement with the largest number of LMW heparins; potencies were assigned by taking the mean of all the anti-Xa assays, and the mean of the thrombin and APTT assays, to represent the two major groups of activities. Preparation 85/600 has been established by WHO as the 1st International Standard for LMW heparin, with potencies of 1,680 iu/ampoule by anti-Xa assays and 665 iu/ampoule by thrombin inhibition and APTT assays.

Key words

Low molecular weight heparin - Assays - Standardisation

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References

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