Thromb Haemost 1994; 71(03): 280-283
DOI: 10.1055/s-0038-1642430
Original Article
Schattauer GmbH Stuttgart

Thrombin-Based Antithrombin Assays Show Overestimation of Antithrombin III Activity in Patients on Heparin Therapy due to Heparin Cofactor II Influence[*]

Jürgen Bohner
The Institut für Laboratoriumsmedizin, Städtisches Klinikum Fulda, Fulda, Germany
,
Klaus-Werner von Pape
The Institut für Laboratoriumsmedizin, Städtisches Klinikum Fulda, Fulda, Germany
,
Mathias Blaurock
The Institut für Laboratoriumsmedizin, Städtisches Klinikum Fulda, Fulda, Germany
› Author Affiliations
Further Information

Publication History

Received: 04 August 1993

Accepted after revision 12 December 1993

Publication Date:
06 July 2018 (online)

Summary

An extensive comparison has been performed on the clinical chemistry automate Hitachi 717 between thrombin-and Factor Xa-based methods for determination of antithrombin III activity. In 460 patients who did not receive any heparin therapy the agreement between assays was in general close although the thrombin-based methods resulted in slightly higher assignments of 0.3—2.6% antithrombin III activity. The discrepancy was, however, substantial in plasmas from patients receiving heparin of >20000 IU/day, resulting in plasma levels of heparin of 0.8-1.2 IU/ml. Thus, analysis of 102 patients showed that the thrombin-based methods resulted in, on average, 7-16% higher assignment of antithrombin III activity as compared to the Factor Xa-based method used.

Addition of antibodies to antithrombin III and heparin cofactor II revealed that the discrepancy was primarily due to contribution of heparin cofactor II activity in the thrombin-based methods. The results thus suggest that the Factor Xa-based antithrombin III activity method provides more valid results in patients on heparin therapy.

* In memory of Professor Dr. Manfred Eggstein.