Factor II (prothrombin) assay
.Factor II (Prothrombin) Assay
The prothrombin assay is a laboratory test used to measure the concentration of the clotting factor Factor II (Prothrombin) in the blood. This test helps diagnose and monitor coagulation disorders such as hemophilia and deep vein thrombosis. It can also be used to check for an inherited disorder called Factor II deficiency.
Preparation
No fasting or special preparation is required before a prothrombin assay. However, the patient may need to be on a drug holiday if they are taking anticoagulants.
Procedure
The prothrombin assay is typically conducted in both a manual and automated method. In the manual method, the patient’s plasma is incubated with reagents that cause the prothrombin to form a clot. This clotting time is then measured as an indication of the prothrombin concentration in the blood. In the automated method, the patient’s blood sample is analyzed with the use of reagents and a machine to measure the prothrombin activity.
Types
There are two main types of prothrombin assays: the activated partial thromboplastin time (APTT) and the thrombin time (TT). The APTT measures the amount of time it takes for a clot to form in a test tube that has been treated with special chemicals (clot activators). The TT measures the amount of time it takes for a clot to form in the presence of thrombin, which is an enzyme involved in clotting.
Risks
The prothrombin assay is usually a risk-free procedure. However, some patients may experience mild discomfort during the sample collection process.
Why Should the Test be Performed?
- To diagnose and monitor coagulation disorders such as hemophilia and deep vein thrombosis.
- To check for an inherited disorder called Factor II deficiency.
- To assess the risk of clotting during a surgical procedure.
When Should the Test be Done?
The prothrombin assay should be performed when there is a suspicion of a clotting disorder or as part of preoperative evaluation. It can also be done when a patient takes anticoagulants (such as warfarin) to make sure that the dose is appropriate.