Blood Res.  2016 Sep;51(3):171-174. 10.5045/br.2016.51.3.171.

Establishing the heparin therapeutic range using aPTT and anti-Xa measurements for monitoring unfractionated heparin therapy

• Byun JH
• Jang IS
• Kim JW
• Koh EH

• KMID: 2353497
• DOI: http://doi.org/10.5045/br.2016.51.3.171

Abstract

BACKGROUND
Unfractionated heparin (UFH) has unstable pharmacokinetics and requires close monitoring. The activated partial thromboplastin time (aPTT) test has been used to monitor UFH therapy for decades in Korea, but its results can be affected by numerous variables. We established an aPTT heparin therapeutic range (HTR) corresponding to therapeutic anti-Xa levels for continuous intravenous UFH administration, and used appropriate monitoring to determine if an adequate dose of UFH was applied.
METHODS
A total of 134 ex vivo samples were obtained from 71 patients with a variety of thromboembolisms. All patients received intravenous UFH therapy and were enrolled from June to September 2015 at Gyeongsang National University Hospital. All laboratory protocols were in accordance with the Clinical and Laboratory Standards Institute guidelines and the College of American Pathologist requirements for aPTT HTR.
RESULTS
An aPTT range of 87.1 sec to 128.7 sec corresponded to anti-Xa levels of 0.3 IU/mL to 0.7 IU/mL for HTR under our laboratory conditions. Based on their anti-Xa levels, blood specimen distribution were as follows: less than 0.3 IU/mL, 65.7%; 0.3-0.7 IU/mL (therapeutic range), 33.6%; and more than 0.7 IU/mL, 0.7%. No evidence of recurring thromboembolism was observed.
CONCLUSION
Using the conventional aPTT target range may lead to inappropriate dosing of UFH. Transitioning from the aPTT test to the anti-Xa assay is required to avoid the laborious validation of the aPTT HTR test, even though the anti-Xa assay is more expensive.

Keyword

Chromogenic anti-Xa test assay; Unfractionated heparin (UFH); Activated partial thromboplastin time (aPTT); Heparin therapeutic range (HTR)

MeSH Terms

Heparin*
Humans
Korea
Partial Thromboplastin Time
Pharmacokinetics
Thromboembolism
Heparin

Figure

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  Fig. 1 Correlation of aPTT and anti-Xa assay results. The aPTT range calculated from the linear regression equation, which corresponds to 0.3 IU/mL to 0.7 IU/mL, was 87.1 sec to 128.7 sec.

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