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Explanation of analyzes

Prothrombin (by Kviku) and prothrombin index, prothrombin rate

The prothrombin assay is part of the coagulogram coagulation study. In addition to the activity of this protein, indicators such as PI (prothrombin index, or PTI) and PV (prothrombin time) are also determined, which allow estimating the clotting rate. The normal values ​​of prothrombin in women, men and children, as well as the reasons for their deviation from the norm, are described in detail later.


Prothrombin - what is it?

Prothrombin is a high molecular weight protein compound involved in blood clotting. Its production takes place in the liver in the presence of many substances. In particular, vitamin K, the deficiency of which leads to the synthesis of the wrong molecules of prothrombin - they form thrombi that disrupt the movement of blood and can lead to death.


An analysis of prothrombin is needed to assess blood coagulability, and the most accurate and universal method of investigation is PC - prothrombin by Quik. What it is? This test reveals the prothrombin activity in the patient's blood as compared to that in the control portion of plasma. This is the ratio of the clotting time of the patient's plasma to the time of this process in the sample.

The analysis is named after the scientist A. Kvik, who proposed this method. In the test results, prothrombin by Quiku is expressed as a percentage. In the international nomenclature he was given the number II, because he was discovered second after fibrinogen.

The Quiku assay is used not only to evaluate the activity of blood clotting elements, but also to study the functioning of the gastrointestinal tract and liver. The PC test is more versatile than prothrombin time and prothrombin index tests.

List of indications for the analysis of prothrombin by Kviku:

  • impaired blood clotting;
  • liver disease;
  • antiphospholipid syndrome - increased thrombus formation due to autoimmune causes;
  • blood cancer;
  • pathology, in which the development of vitamin K is disrupted (blockage of the biliary tract, poor digestibility of food in the intestines, etc.).

Reference: vitamin K is produced by bacteria in the intestine and takes an active part in the formation of prothrombin. At the speed of blood clotting, both its shortage and excess are negatively reflected.

A PC test is necessary to control the hemocoagulation system during the use of anticoagulants - Heparin, Warfarin and others. The structure of the blood and its composition also change with the onset of menopause in women (after 45 years), which is a risk factor for the development of cancer. Therefore, at this age it is especially important to regularly take an analysis for prothrombin.

Prothrombin time - what is it?

Prothrombin by Quique

Depending on the causes of bleeding, the blood can begin to curl in two ways - internal or external. The first is activated if the vessels are damaged from the outside - as a result of bruises, cuts, scratches, bites, abrasions. The internal way works when the integrity of the wall of the blood vessel was broken from the inside - under the influence of toxins, pathogenic microorganisms, antibodies.

Prothrombin time is an indicator that reflects the work of the internal pathway in the hemocoagulation system.

It reflects the effectiveness of "repair" of vessels that have been damaged by compounds circulating along the bloodstream. In the analysis results, prothrombin time can be referred to as PV, ecombipl RT or RT.

Prothrombin time is increased , in comparison with the norm, under the following conditions:

  • lack of vitamin K;
  • the initial stage of DIC syndrome;
  • pathologies of the liver;
  • taking drugs from the group of anticoagulants - Tromboass, Agregal, Warfarin, Heparin and others;
  • hemorrhagic diathesis of newborns;
  • inflammation and blockage of the biliary tract;
  • Zollinger-Ellison syndrome;
  • violation of absorption in the intestine of fats;
  • deficiency of coagulation factors - fibrinogen , prothrombin, AC-globulin, proconvertin and Stewart-Prower factor.

The lower the concentration of prothrombin in the blood, the higher the prothrombin time, because the process of blood coagulation occurs more slowly at the same time.

Prothrombin time is decreased if such conditions occur:

  • pregnancy;
  • DIC-syndrome;
  • high level of antithrombin-III and other anticoagulants produced by the body;
  • deviation from the norm of hematocrit - the ratio of the volume of blood cells to the volume of plasma.

Low prothrombin time during the test may be due to the long storage of plasma before the study and violations when taking blood.

Prothrombin index

Prothrombin index The prothrombin index is an indicator that reflects the rate at which blood clotting starts along the internal pathway. It is calculated on the basis of prothrombin time, so its increase is observed with the same disorders in the body as the increase in PV, as well as the decrease.

To determine the PTI, the coagulation time of the patient's plasma is divided by this value in the control sample. Normally the result should be 95-105%.

The accuracy of the prothrombin index analysis depends on the sensitivity of the drugs used in the laboratory. Therefore, it can not be called universal, in contrast to the test for prothrombin by Kviku.

Increased prothrombin

If the Quik test for prothrombin is elevated and shows high values ​​(up to 150% or more), the reason for this may be:

  • DIC syndrome;
  • Cholestasis and other diseases that reduce the activity of vitamin K;
  • diseases that disrupt the functioning of fibrin;
  • hereditary and acquired pathologies, leading to a deficiency of coagulation factors ( amyloidosis , liver disease, nephrotic syndrome).

Elevated prothrombin also appears with prolonged intake of drugs:

  • antibiotics;
  • diuretic drugs;
  • Aspirin;
  • indirect anticoagulants;
  • anabolic;
  • Methotrexate;
  • laxatives;
  • nicotinic acid;
  • Heparin and other coagulation inhibitors.

Prothrombin Rate, Table

The extreme values ​​of PCs are figures below 78 and above 142%. The norms of prothrombin according to Kvik are presented in the table.

Age, years Limits of the norm PK / td>
until 6 80-100
6-12 79-102
12-18 78-110
18-25 82-115
25-45 78-135
45-65 from 78 to 142

The norms of prothrombin in men and women of the same age group do not differ. The normal values ​​of prothrombin time for both sexes are 9-12 sec. The norm of prothrombin in the blood of women expecting a child is slightly higher than usual values.

Low prothrombin

Low Quim prothrombin always indicates the excessive formation of thrombi and is provoked by such states as:

  • pregnancy and postpartum period;
  • vein thrombosis;
  • penetration of thromboplastin into blood vessels due to tissue damage;
  • high blood viscosity (polycythemia).

The decrease in PC can be explained by such a dependence - the activity of the prothrombin protein is high, the blood is folded faster compared to the control plasma sample, therefore, the Quik's prothrombin test is below normal.

Low Quim prothrombin can also be caused by the use of Mercaptopurine, hormonal contraceptives and other drugs that increase the density of blood.

Prothrombin during pregnancy

Coagulogram is an obligatory part of tests for pregnant women. Evaluation of this study, including prothrombin tests, allows timely detection of dangerous for the health of the child and the future mother of the condition.

Prothrombin by Kviku at pregnancy in norm or rate is a little lowered, that is activity of system of a coagulability increases. This is due to the appearance of a new blood circulation and with the preparation of the organism for the forthcoming birth and possible blood loss.

A very low PC can provoke the development of thrombosis, and its increase in pregnant women can cause severe bleeding during labor, including internal.

Severe bleeding when the Rh factor of a woman and the fetus is incompatible can cause a hemolytic shock due to the mixing of the blood of the mother and the baby. This is one of the frequent causes of postpartum mortality. To avoid this, in this situation, not only monitor and monitor the state of the clotting system, but also introduce immunoglobulins destroying potentially dangerous antibodies at week 28 of pregnancy.

  • The norm of prothrombin index for women bearing a child is 80-100%. At its high values, in order to avoid thrombosis and other complications, preparations that reduce the increased activity of coagulability are shown.
  • Low PI, on the contrary, carries the risk of bleeding. The normal value of prothrombin time for pregnant women is 11-18 sec. In pregnancy, any deviation from the norm in the coagulogram is a reason for careful examination and in most cases - hospitalization.

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