The ACT test can be used to monitor the effects of anticoagulation, such as those of high-dose heparin, before, during, and shortly after procedures requiring intense administration of anticoagulants, such as cardiac bypass surgery, interventional cardiology, thrombolysis, extracorporeal membrane oxygenation (ECMO), and continuous dialysis.
Also Known as | Activated Clotting Time, ACT, Activated Coagulation Time |
Test Purpose | To monitor treatment with heparin or other blood-thinning medications (anticoagulants) when undergoing heart bypass surgery, coronary angioplasty, or dialysis |
Test Preparations | No Preparation Required |
Test Components | ACT Test |
Specimen | Whole Blood |
Stability Room | N/A |
Stability Refrigerated | N/A |
Stability Frozen | N/A |
Method | Lee and white |
Download Report | Download Report |

Why get tested?
To monitor treatment with heparin or other anticoagulant drugs (anticoagulants) when undergoing heart bypass surgery, coronary angioplasty, or dialysis
When to get tested?
When you are receiving high doses of heparin to prevent clotting during and after surgical procedures such as heart bypass.
when heparin levels are too high to allow monitoring with a partial thromboplastin time (PTT).
When a quick result is necessary to control the treatment.
Interpretation
A normal activated clotting time (ACT) indicates that the blood tested does not contain heparin or that all heparin is inhibited by protamine (reversal of postoperative anticoagulation).
ACT is intended to monitor the anticoagulant effect of unfractionated heparin. ACT target values may depend on the specific device and clinical scenario. ACT prolongation may also indicate coagulation factor deficiency, severe thrombocytopenia, or severe platelet dysfunction.
Sample Required:
Specimen: Whole blood
Collection: Blood (usually 0.5-1 mL) from venous/arterial vessel; indwelling or extracorporeal line is collected into the plastic syringe/tube (see image below) and immediately placed/poured into the device cuvette/cartridge
Storage: Whole blood specimen should be processed within 1 minute (or 2 min if specimen contains therapeutic level of unfractionated heparin)
Normal values:
Source 1
The normal range for ACT is 70-120 Second
Source 2
- 70 to 120 seconds is the usual amount of time for blood to clot without heparin.
- 180 to 240 seconds is the usual amount of time for blood to clot with heparin. This is called the therapeutic range.
Possible References Used