Tests for patients on DOACs
What the PT, aPTT and thrombin time can and can't tell you on a DOAC, drug-calibrated anti-Xa assays and the dilute thrombin time, when a level changes management (bleeding, urgent surgery, thrombolysis), and how DOACs distort thrombophilia and heparin assays.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- DOACs are given at fixed doses without monitoring. A level is useful only when the answer changes what you do next.
- Routine tests are unreliable: a normal PT or aPTT doesn't exclude a relevant level of apixaban, and only the thrombin time is a dependable screen, for dabigatran alone.
- To measure the drug, use a drug-calibrated anti-Xa assay (rivaroxaban, apixaban, edoxaban) or a dilute thrombin time (dabigatran), reported in ng/mL.
Loading the rest of the note…
Finished reading?
Sources
- New oral anticoagulants: a practical guide on prescription, laboratory testing and peri-procedural/bleeding managementAU/NZTran H et al. (Australasian Society of Thrombosis and Haemostasis), Intern Med J 2014;44:525-36, 2014
- Laboratory testing in patients treated with direct oral anticoagulants: a practical guide for cliniciansDouxfils J et al. (ISTH SSC), J Thromb Haemost 2018;16:209-19, 2018
- International Council for Standardization in Haematology (ICSH) recommendations for laboratory measurement of direct oral anticoagulantsGosselin RC et al., Thromb Haemost 2018;118:437-50, 2018
- When and how to use antidotes for the reversal of direct oral anticoagulants: guidance from the SSC of the ISTHLevy JH et al., J Thromb Haemost 2016;14:623-7, 2016
- Lupus anticoagulant detection in anticoagulated patients: guidance from the ISTH SSCTripodi A et al., J Thromb Haemost 2020;18:1569-75, 2020
- Perioperative management of patients with atrial fibrillation receiving a direct oral anticoagulant (PAUSE)Douketis JD et al., JAMA Intern Med 2019;179:1469-78, 2019
- Andexanet for factor Xa inhibitor-associated acute intracerebral hemorrhage (ANNEXA-I)Connolly SJ et al., N Engl J Med 2024;390:1745-55, 2024
- Eliquis (apixaban): summary of product characteristicsEuropean Medicines Agency, Current EPAR product information
- Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: ASRA Pain Medicine evidence-based guidelines (fifth edition)Kopp SL et al., Reg Anesth Pain Med 2025, 2025
- RCPA Manual: coagulation testsAU/NZRoyal College of Pathologists of Australasia
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy