Quick test or INR test – are associated with oral anticoagulant therapy (anticoagulant tablets – e.g. Warfarin). Maybe you’re simply not sure exactly what it is and what it means. In this article we will try to explain the Quick, PT- INR tests.
(Quick) PT test
First, let’s talk about the Quick test or PT test. PT represents prothrombin time (Prothrombin Time). It is a measure of how quickly blood forms a blood clot. The traditional method of PT test is done by taking a blood sample and sending it to the laboratory. In the laboratory, a substance called reagent is added to your blood. This reagent causes the blood begins to coagulate. The PT test result is time in seconds that is needed for blood clotting.
There are many reagents that can be used when the PT test is performed. Given that each of these agents works a little differently, the result obtained by one of the PT reagent cannot be compared with the result obtained by another agent. For comparison, results of tests with different reagents must be studied, the result must be converted to standard units that can be compared regardless of the agent used. These standard units are known as INR units.
INR stands for International Normalized Ratio (International Normalized Ratio). As its name suggests, the result of one INR can be compared with any other, regardless of how the result was obtained. So, INR is really just the basic unit used to express the PT test result.
INR results and target range
There are a few things worth noting about INR test. Firstly, a man whose blood is clotting normally and who is not on anticoagulant therapy should have approximately INR 1. The higher your INR, the longer it takes your blood to clot. In other words, as INR increases above a given level, and the risk of bleeding events associated with bleeding increases. On the other hand, when the INR falls below a given level, the risk of excessive blood clotting and thrombosis increases.
The ideal target INR range will vary from person to person depending on various factors such as the reason for use of anticoagulants, intercurrent illness, and a number of other issues. Your doctor will determine the proper INR range. The most common INR target range for warfarin patients is somewhere between 2.0 and 4.0. Most often the target range set between 2.0 and 3.0 or between 2.5 and 3.5 according to the diagnosis. Doctors usually avoid setting a target INR range of 5 or more, because the risk of bleeding is significantly increased with INR above 5.
Once your doctor chooses the appropriate target INR range, he/she will adjust your anticoagulant therapy so your INR will be within the target range. If your INR rises above the upper limit of its range, the risk of bleeding and bleeding related events may start to increase. If your INR falls below the lower limit of your target zone, your risk of a blood clot may increase.
Beware of factors affecting INR!
Numerous factors can affect your INR test result, so it is important that you inform your physician about any changes in your life. For example, you should always consult your doctor before taking new prescription drugs or even over the counter medicines, including herbal products. You should also inform your doctor about changes in your eating, a diet, exercise routine, alcohol use, tobacco use, etc. Good communication with your physician will keep your anticoagulation therapy within safe limits.
It is important to test your INR regularly, so that the correct setting of drug dosage is ensured.
How often to test INR?
This test is carried out by taking a blood sample in the range of about one week to one month.
Many factors can affect blood INR and is therefore in the sake of safe treatment that the INR is checked regularly and the results are recorded. The more frequent monitoring the greater safety of treatment – of course it depends on the individual fluctuations or stability of your INR. The maximum interval between INR tests is 4 weeks.
For additional testing, home or traveling, it is possible to get a CoaguChek device.
Want to know what influences the level of INR? ⇒ Warfarin Diet
Did you know that Warfarin may harm the embryo?