What is the difference between aPTT and ACT?
Both aPTT (activated partial thromboplastin time) and ACT (activated clotting time) tests assess the intrinsic and common pathways. When compared to the aPTT, the ACT test is less sensitive to intrinsic and common pathway problems. If a haemostatic problem is suspected and ACT is “normal,” an aPTT test should be performed. ACT can potentially be prolonged by thrombocytopaenia, while the aPTT test is not affected by low platelet numbers.
