title: Establishing the heparin therapeutic range using aPTT and anti-Xa measurements for monitoring unfractionated heparin therapy.
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 134ex vivosamples 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Laboratory Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju, Korea.
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Byun
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju, Korea.
authors.forename: In-Seok
authors.initials: IS
authors.lastname: Jang
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju, Korea.
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju, Korea.; Institute of Health Sciences, Gyeongsang National University, Jinju, Korea.
authors.forename: Eun-Ha
authors.initials: EH
authors.lastname: Koh
keywords: Activated partial thromboplastin time (aPTT); Chromogenic anti-Xa test assay; Heparin therapeutic range (HTR); Unfractionated heparin (UFH)