Prothrombin time, which is how fast blood clots

Proven content

Prothrombin time is an indicator of the time it takes for blood clots to form. It is a measure of the activity of plasma coagulation factors: I, II, V, VII and X. On its basis, the extrinsic pathway of thrombin activation is assessed. The prothrombin time is influenced by coagulation inhibitors (heparin, anticoagulants).

What is prothrombin time?

Prothrombin Time (PT) is a key indicator of how long a blood clot forms. In people with damaged blood vessels, a number of processes are responsible for stopping bleeding, in which blood clotting factors are involved. These are proteins on which the correct course of the clotting process depends, because they determine the activation and stabilization of the subsequent stages of clotting. Additionally, the prothrombin time is influenced by coagulation inhibitors such as heparin and anticoagulants. We determine the prothrombin time (PT) by taking blood from the patient and checking how the clotting factors that make up the so-called prothrombin syndrome.

Blood coagulation factors

Blood clotting is a complex process involving clotting factors and many other compounds that activate, deactivate and stabilize individual reaction steps. In the prothrombin time study, factor I (fibrinogen), factor II (prothrombin), factor V (proaccelerin), factor VI (proconvertin) and factor X (Stuart-Prower factor) are the main factors.

Measurement of prothrombin time provides important information about clotting, but additional tests are sometimes necessary. A complex test to assess blood clotting is coagulogram. As part of this test, depending on the needs, you can determine a number of different parameters, which include:

1. prothrombin time (PT),
2. thrombin time (TT),
3. Coalion-Kephalin Time (APTT),
4. reptylase time (RT),
5. antytrombina III,
6. fibrinogen concentration,
7. concentration of D-dimers.

Prothrombin time and thrombin time

Thrombin time (TT) is not the same as prothrombin time (PT), but both are related. One of the information provided by the PT test is the activity of prothrombin – this protein factor is responsible for the formation of thrombin. However, the mileage is assessed on the basis of the TT test the last stage of blood clottingduring which fibrinogen is transformed into insoluble fibrin, which is the foundation of the clot that is formed. The already mentioned thrombin, i.e. the blood plasma enzyme, takes part in the process of fibrin formation.

How is prothrombin time determined?

The result of the PT measurement can be presented in various ways (in seconds, percentage of Quick or the range of INR). The longer the prothrombin time, the slower the blood will clot. Prothrombin time results from different laboratories are compared and the INR, i.e. the international normalized ratio, is determined. Both PT and INR are indicators on the basis of which the effect of anticoagulants is assessed, which may, for example, inhibit vitamin K and thus increase the prothrombin time.

When do we do the prothrombin time test?

The prothrombin time is the most important factor in the prophylaxis of diseases related to clotting, especially when surgical treatment is required. Prothrombin time study we perform in the following situations:

1. Monitoring of treatment with anticoagulants – anticoagulants. The PT test is the primary test for monitoring treatment with oral anticoagulants.
2. Suspicion of an intravascular coagulation syndrome.
3. Suspected deficiency and disorders of vitamin K metabolism.
4. Suspected liver damage.
5. Routine assessment before surgery. Patients using preparations from the group of vitamin K antagonists (e.g. warfarin) should have a marked prothrombin time before surgery, in order to avoid excessive bleeding during the procedure.
6. Assessment of the situation after surgery or fracture of the lower limb / pelvis.
7. Assessment of the situation in obese people with advanced varicose veins of the lower extremities.
8. Women using oral hormone replacement therapy or contraception.
9. Pregnant and postpartum women.
10. Diagnostics of congenital and acquired bleeding disorders.
11. Clinical conditions with hypercoagulability and thrombosis.
12. Monitoring of patients after cardiac surgery. This applies especially to the implantation of an artificial heart valve, which makes the patient obligated to take anticoagulant preparations throughout his life. The duration of anticoagulation treatment is shorter for biological valves (usually 3 months).
13. Patients with atrial fibrillation. The risk of blood clots in the right and left atriums is reduced by taking anticoagulants.

Prothrombin time – study

1. Material for the prothrombin time test: citrate plasma.
2. Preparation for the prothrombin time test: fasting (at least 8 hours). Before performing the test, you should be rested and sleepy, it is not recommended to practice physical activity the day before the test is performed. The day to take drugs on a given day should be agreed with the doctor and should be closely related to the purpose of a given test.
3. The course of the examination: one-time blood sampling from a vein in the arm. The puncture is performed with a thin needle and the material is placed in a test tube (it should contain the right amount of sodium citrate). It is also possible to determine INR in special devices made of material taken from the fingertip. It is a simple and safe test that allows the patient to self-control prothrombim time at home. This reduces the time the patient would have to spend in a doctor’s office or hospital. Test result obtained in less than a minute. The advantage of self-monitoring is the possibility of regular and frequent monitoring of PT, so that treatment can be quickly modified if necessary. Devices used for home examination may not be very cheap, but they are useful for patients sentenced to long-term anticoagulant treatment.
4. Time of waiting for the result: 1 day.
5. Norms: 12-18 seconds, INR 0,8-1,2.

Can there be complications after the examination?

Some people are particularly sensitive to blood sampling and therefore faint. Some people experience a slight pain or burning sensation at the injection site. Of course, the blood collection procedure should be performed with the full protection of the patient and staff against infection. Another rare complication may be prolonged bleeding, which is caused by inadequate pressure at the injection site or by a blood clotting disorder. These people may have a bruise at the injection site even after the correct blood sample is taken.

What are the normal values ​​for prothrombin time?

The results of prothrombin time and other tests may vary from lab to lab. This is due to the test method and the type of device on which the blood was tested. For this reason, the given standards may differ slightly from each other and this should be borne in mind when comparing the test results.

1. Normal prothrombin time: 12-18 seconds. This depends largely on the activity of the added thromboplastin.
2. INR ratio: 0,8-1,2. It is used to monitor treatment with oral anticoagulants.

In order to support blood clotting, it is worth supplementing with vitamin K. At Medonet Market you will find supplements with vitamin K, eg Menachinox K2 or Menachinox K2 200 available at a promotional price.

Analysis of the results of prothrombin time studies

In patients who are not taking anticoagulants any increase in PT or INR above the upper limit should be consulted. People taking anticoagulants in the form of: warfarin, acenocoumarol, dicoumarol, blood clotting time is controlled using the INR indicator, which allows you to adjust the appropriate dose of the drug.

1. INR <2,0:sugeruje złe przyjmowanie leku lubzbyt małą dawkę,
2. INR 2,0-3,0: you can name ittherapeutic rangewhich allows the clotting time to be extended with a low risk of life-threatening and health-threatening haemorrhages. This indicates a well-chosen dose of the drug and the appropriate way of taking it,
3. INR> 5,0: this value indicates a risk of haemorrhage, it may also suggest incorrect use of the drug by the patient (too often, too much) or an inadequate dose.

Each patient reacts differently to a given preparation, so it is important to constantly consult a doctor to adjust the appropriate drug and dose.

What does the prothrombin index below normal mean?

A shortened prothrombin time may suggest the presence of:

1. pregnancy,
2. the perinatal period,
3. thrombosis,
4. thrombophilia (hypercoagulability),
5. excessive factor VII activity.

What does the prothrombin index above normal mean?

The prothrombin index below normal is observed in people:

1. suffering from chronic diseases of the liver parenchyma,
2. with vitamin K deficiencies,
3. suffering from leukemia,
4. suffering from Addison-Biermer disease,
5. treated with anticoagulants,
6. with uremia,
7. poisoned with coumarin derivatives,
8. suffering from congenital deficiencies of clotting factors (II, V, VII, X),
9. struggling with disseminated intravascular coagulation,
10. having fibrinogen deficiency,
11. suffering from systemic lupus,
12. treated with clotting inhibitors (e.g. heparin).

Do you need interpretation of test results? Are you worried about your symptoms? Contact your doctor. Make an online teleconsultation with your family doctor at haloDoctor.pl to get answers to your questions.

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