{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T03:39:50Z","timestamp":1792381190013,"version":"4.4.0"},"reference-count":31,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T00:00:00Z","timestamp":1779235200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T00:00:00Z","timestamp":1779235200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Int J Lab Hematology"],"published-print":{"date-parts":[[2026,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>Borderline prolongation of routine clotting assays\u2014particularly the activated partial thromboplastin time (aPTT)\u2014is a common interpretative challenge in laboratory hematology. These reproducible but mildly prolonged results often lie just beyond the upper reference limit and can trigger unnecessary follow\u2010up, delays, or misinterpretation. Conventional tools such as 1:1 mixing studies may appear corrective due to dilutional masking of weak inhibitors, residual anticoagulants, or low\u2010grade lupus anticoagulant (LA) activity, especially in assays with limited sensitivity. In our laboratory, borderline prolongations prompt a structured, hypothesis\u2010driven workflow that escalates interpretative resolution in sequential steps. We begin with verification of analytical validity and exclusion of confounders (e.g., DOACs, pre\u2010analytical errors), then apply conventional mixing studies interpreted via quantitative correction indices (e.g., Rosner, percent correction). When results remain indeterminate or discordant, we escalate to enhanced mixing ratios (e.g., 4:1, 1:4), followed by factor assays and dilutional analysis including parallelism assessment. Here, we outline an integrated decision\u2010support framework for investigating borderline aPTT prolongation. The framework aligns traditional and enhanced mixing strategies with factor\u2010level interpretation into a coherent, stepwise pathway featuring explicit stop\u2013go points. It is intended for use in advanced or referral coagulation laboratories and emphasizes interpretative rigor over binary thresholds. By optimizing existing tools within a layered interpretative structure, this approach seeks to reduce false reassurance and enhance clarity in borderline aPTT interpretation.<\/jats:p>","DOI":"10.1111\/ijlh.70156","type":"journal-article","created":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T13:26:22Z","timestamp":1779283582000},"page":"951-960","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["How I Investigate Borderline Prolonged\n                    <scp>aPTT<\/scp>\n                    : An Integrated Laboratory Approach to Mixing Studies and Factor Analysis"],"prefix":"10.1111","volume":"48","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8842-2360","authenticated-orcid":false,"given":"Nikolaos","family":"Androulakis","sequence":"first","affiliation":[{"name":"Hematology Laboratory University Hospital of Iraklion  Iraklion Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eleni","family":"Nioti","sequence":"additional","affiliation":[{"name":"Hematology Laboratory University Hospital of Iraklion  Iraklion Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antonios","family":"Dilintas","sequence":"additional","affiliation":[{"name":"Hematology Laboratory University Hospital of Iraklion  Iraklion Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christina","family":"Kalpadakis","sequence":"additional","affiliation":[{"name":"Hematology Laboratory University Hospital of Iraklion  Iraklion 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