{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T22:41:21Z","timestamp":1792708881421,"version":"4.5.0"},"reference-count":7,"publisher":"Georg Thieme Verlag KG","issue":"08","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Semin Thromb Hemost"],"published-print":{"date-parts":[[2026,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Low molecular weight heparin (LMWH) remains a widely utilized parenteral anticoagulant in hospital and outpatient settings for thromboprophylaxis and treatment of venous thromboembolism. While LMWH typically does not require routine monitoring due to predictable pharmacokinetics, anti-factor Xa (anti-Xa) monitoring is indicated in specific populations, including those with renal impairment, extremes of body weight, pregnancy, or unexplained treatment failure. LMWH monitoring relies exclusively on chromogenic anti-Xa assays, as LMWH's predominant anti-Xa activity with minimal anti-IIa effect renders activated partial thromboplastin time insensitive. Therapeutic targets are context-dependent: peak anti-Xa levels of 0.5 to 1.2 U\/mL for twice-daily therapeutic dosing or 1.0 to 2.0 U\/mL for once-daily dosing, measured 3- to 5-hour postdose. We report external quality assessment findings for anti-Xa testing of LMWH from the past 6 years (2020\u20132025 inclusive) using RCPAQAP (Royal College of Pathologists of Australasia Quality Assurance Program) data, an international program with approximately 150 laboratory enrolments. Four samples are assessed annually at varied LMWH concentrations (0, 0.2\u20130.3, 0.5\u20130.6, 0.8\u20131.0 U\/mL). Good reproducibility was demonstrated for duplicate samples across surveys. Coefficient of variation data revealed moderate variability (10\u201325%) for detectable LMWH levels, lower than unfractionated heparin (UFH) monitoring variability. Method-related differences were observed, with Siemens Innovance anti-Xa assays yielding slightly higher values than Werfen HemosIL or Stago STA assays. Participant interpretations of LMWH levels (below\/within\/above therapeutic range) showed greater variability than UFH due to multiple valid therapeutic ranges for LMWH depending on dosing context. Overall, laboratories demonstrated acceptable analytical and interpretative performance for LMWH monitoring, which should provide some reassurance to both patients and their clinical carers.<\/jats:p>","DOI":"10.1055\/a-2900-7026","type":"journal-article","created":{"date-parts":[[2026,7,4]],"date-time":"2026-07-04T00:13:08Z","timestamp":1783123988000},"page":"967-974","source":"Crossref","is-referenced-by-count":1,"title":["External Quality Assessment for Low Molecular Weight Heparin Monitoring in the Australasia\/Asia-Pacific Region"],"prefix":"10.1055","volume":"52","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2103-1661","authenticated-orcid":false,"given":"Emmanuel J.","family":"Favaloro","sequence":"additional","affiliation":[{"name":"Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, Australia","department":["Department of Haematology, Sydney Centres for Thrombosis and Haemostasis"]},{"name":"Westmead Hospital, Australia","department":["Sydney Centres for Thrombosis and Haemostasis, Research and Education Network (REN)"]},{"name":"Charles Sturt University, Australia","department":["Faculty of Science and Health, School of Dentistry and Medical Sciences"]},{"name":"University of Sydney, Westmead Hospital, Australia","department":["Faculty of Medicine and Health, School of Medical Sciences"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-1656-2349","authenticated-orcid":false,"given":"Sandya","family":"Arunachalam","sequence":"additional","affiliation":[{"name":"Royal College of Pathologists of Australasia, Australia","department":["RCPAQAP Haematology"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8237-6743","authenticated-orcid":false,"given":"Leonardo","family":"Pasalic","sequence":"additional","affiliation":[{"name":"Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, Australia","department":["Department of Haematology, Sydney Centres for Thrombosis and Haemostasis"]},{"name":"Westmead Hospital, Australia","department":["Sydney Centres for Thrombosis and Haemostasis, Research and Education Network (REN)"]},{"name":"University of Sydney, Westmead Hospital, Australia","department":["Westmead Clinical School"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"194","published-online":{"date-parts":[[2026,7,3]]},"reference":[{"issue":"03","key":"ref1","doi-asserted-by":"crossref","first-page":"425","DOI":"10.3390\/biom16030425","article-title":"Heparin anticoagulant therapy and its monitoring","volume":"16","author":"B Reardon","year":"2026","journal-title":"Biomolecules"},{"issue":"06","key":"ref4","doi-asserted-by":"crossref","first-page":"632","DOI":"10.1055\/s-0032-1321954","article-title":"External quality assurance for heparin monitoring","volume":"38","author":"R A Bonar","year":"2012","journal-title":"Semin Thromb Hemost"},{"issue":"11","key":"ref5","doi-asserted-by":"crossref","first-page":"1921","DOI":"10.1515\/cclm-2020-0130","article-title":"Quality performance for indirect Xa inhibitor monitoring in patients using international external quality data","volume":"58","author":"M J Hollestelle","year":"2020","journal-title":"Clin Chem Lab Med"},{"issue":"06","key":"ref6","doi-asserted-by":"crossref","first-page":"700","DOI":"10.3390\/biomedicines9060700","article-title":"Optimization of heparin monitoring with anti-FXa assays and the impact of dextran sulfate for measuring all drug activity","volume":"9","author":"J Amiral","year":"2021","journal-title":"Biomedicines"},{"issue":"01","key":"ref7","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1111\/ijlh.12918","article-title":"The importance of commutability in material used for quality control purposes","volume":"41","author":"I Jennings","year":"2019","journal-title":"Int J Lab Hematol"},{"issue":"10","key":"ref8","doi-asserted-by":"crossref","first-page":"2613","DOI":"10.1111\/jth.14969","article-title":"Monitoring unfractionated heparin therapy: lack of standardization of anti-Xa activity reagents","volume":"18","author":"M Smahi","year":"2020","journal-title":"J Thromb Haemost"},{"issue":"04","key":"ref9","doi-asserted-by":"crossref","first-page":"720","DOI":"10.1111\/ijlh.14447","article-title":"Activated protein C resistance testing: an update from Australasia\/Asia-Pacific","volume":"47","author":"E J Favaloro","year":"2025","journal-title":"Int J Lab Hematol"}],"container-title":["Seminars in Thrombosis and Hemostasis"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/www.thieme-connect.de\/products\/ejournals\/pdf\/10.1055\/a-2900-7026.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T22:33:35Z","timestamp":1792708415000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.thieme-connect.de\/DOI\/DOI?10.1055\/a-2900-7026"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,3]]},"references-count":7,"journal-issue":{"issue":"08","published-online":{"date-parts":[[2026,10,22]]},"published-print":{"date-parts":[[2026,11]]}},"URL":"https:\/\/doi.org\/10.1055\/a-2900-7026","archive":["Portico","CLOCKSS"],"relation":{},"ISSN":["0094-6176","1098-9064"],"issn-type":[{"value":"0094-6176","type":"print"},{"value":"1098-9064","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,3]]}}}