PT-INR
Coagulation tests must be determined directly and cannot be sent. Blood sampling must therefore take place at the Mönchengladbach location.
You can also try to get this determined at your local thrombosis service
ThePT-INR(citrate tube) is used to determine how long it takes for a blood clot to form.
INR stands for International Normalized Ratio. PT stands for coagulation.
Blood coagulation is a highly complex process involving a series of successive reactions between different coagulation factors (substances that play a role in coagulation). Nearly all coagulation factors are produced in the liver. In the final reaction steps, the blood coagulation factor prothrombin is converted into thrombin. Thrombin then converts fibrinogen into fibrin, which ultimately forms a blood clot. The time it takes for a clot to form in the blood sample is called prothrombin time and is measured in seconds.
Since there are differences between laboratories in the technique used to measure a prothrombin time, the results may differ from one laboratory to another. In order to correct these differences (so that each laboratory reports the same results), the measured prothrombin time is expressed in a so-called ratio, namely thePT-INR, also known as `INR` (International Normalized Ratio).
ThePT-INR is thus a standardized method for measuring the prothrombin time and is only used in patients who are taking blood thinners.
ThePT-INR is used to check whether a patient is properly adjusted to blood thinners (the right drug and the right dose). Blood thinners (oral anticoagulants, vitamin K antagonists such as coumarins) inhibit the formation of blood clots in the body. Blood thinners are prescribed for patients who have an increased risk of developing a blood clot (thrombosis). For example after surgery, a broken bone or if someone has had a thrombosis before.
If a patient has to start using blood thinners, the doctor will refer the patient to the thrombosis service. The thrombosis service regularly measures thePT-INR to ensure that the dose of the blood thinners is correct. An overdose can lead to bleeding, including nose, stomach or brain haemorrhage. An underdose can lead to the development of, for example, a thrombosis leg (a blood clot in the leg's vessels). Because it is difficult to predict how a patient will respond to treatment with blood thinners, regular monitoring of thePT-INR is necessary. A simple illness like a cold or taking certain medication can already influence the effect of blood thinners.
ThePT-INR indicates how much slower a patient's blood clots compared to someone not taking anticoagulants. AnINR result of 2.0 means that the blood is clotting 2.0 times slower than normal. A patient taking anticoagulants should generally have anINR between 2.5 and 3.5. In the case that a patient has a very increased risk of a blood clot (e.g. after having an artificial valve in the heart), the patient is set to a higherINR, namely between 3.5 and 4.5.
PT-INR increased relative to the target value:
APT-INR result that is too high indicates that blood coagulation is too slow, which may cause unwanted bleeding. In this case the dosage of the blood thinner will usually be reduced by the physician. It is very important to follow the dosage as prescribed by the physician (thrombosis service). If thePT-INR value is much too high, the physician or anticoagulation clinic may prescribe vitamin K in order to lower thePT-INR again. However, the effect of vitamin K is only noticeable after more than 8 hours.
AberrantPT-INR:
Use of some medications can affect thePT-INR rash. Antibiotics, aspirin, and cimetidine can increase the rash, while sleep medications (e.g. barbiturates), the "pill," and vitamin K can lead to a decrease. Certain foods, including red meat, liver, green tea, broccoli, and soybeans are high in vitamin K and thus may affect thePT-INR rash. Alcohol consumption also affects thePT-INR. It is important that the doctor is aware of the recent use of these substances so that thePT-INR result can be assessed correctly.
Coagulation analyses (coagulation tests) are particularly sensitive to errors in pre-analysis (blood collection, sample transport). Take blood samples under conditions that are as stress-free as possible.We therefore recommend that you request this test from your local GP, or if this is not possible, to have the blood taken directly at the lab in Monchengladbach.
