Prothrombin, INR (prothrombin time, PT, Prothrombin, INR)

Stroke

34149 August 11

IMPORTANT!

The information in this section cannot be used for self-diagnosis and self-treatment.
In case of pain or other exacerbation of the disease, diagnostic tests should be prescribed only by the attending physician. To make a diagnosis and properly prescribe treatment, you should contact your doctor. We remind you that independent interpretation of the results is unacceptable; the information below is for reference only.
Coagulogram (screening): indications for use, rules for preparing for the test, interpretation of the results and normal indicators.

Indications for the purpose of the study

Coagulogram (hemostasiogram) is a comprehensive hematological study aimed at assessing the state of the hemostasis system (blood clotting), or blood clotting indicators. The hemostasis system includes blood cells (platelets) and specific substances (clotting factors) dissolved in blood plasma and contained in platelets. When the integrity of the vessel wall is violated, the coagulation system is activated and a blood clot is formed, preventing blood loss.

Some time after the bleeding stops, fibrinolysis begins - the process of dissolving the blood clot after restoring the damaged vessel wall to resume blood flow.

Indications for a coagulogram are conditions accompanied by increased bleeding or, conversely, increased thrombus formation.

Increased bleeding leads to hemorrhagic syndrome. It is manifested by the formation of hematomas, pinpoint hemorrhages under the skin (petechiae), bleeding of the mucous membranes (nosebleeds, bleeding from the gums), the appearance of blood in the stool, urine, prolonged menstrual bleeding, as well as possible hemorrhages in the internal organs and body cavities. The most dangerous manifestation of hemorrhagic syndrome is hemorrhage in the brain - hemorrhagic stroke, which can lead to rapid impairment of brain function, including death. A hereditary disease associated with blood clotting disorders (decreased or absent clotting factors) is called hemophilia.

The opposite situation - thrombosis - is the formation of blood clots (thrombi) inside blood vessels, preventing the free flow of blood.

People with obesity, diabetes mellitus, heart rhythm disturbances (the most significant of which are atrial fibrillation and flutter), low physical activity, and patients after major operations (for example, joint replacement, heart valve replacement, emergency operations, etc.) are at risk of increased thrombosis. , with varicose veins, previous myocardial infarctions, strokes, and various autoimmune diseases.

Thrombosis in a certain area of ​​the vascular bed is accompanied by an acute or gradual disruption of the blood supply to any organ with disruption of its functions and subsequent tissue necrosis.

In addition to the above conditions, a coagulogram is performed before operations to assess the risk of bleeding, when prescribing certain medications, and also necessarily in case of liver diseases, since most of the proteins of the blood coagulation system are synthesized in this organ.

Preparation for the procedure

The essence of a coagulogram is to assess the activity of proteins of the blood coagulation system.
Therefore, proper preparation for this analysis is extremely important. Blood is taken on an empty stomach; the last meal should be at least 8-10 hours before the test. It is recommended to exclude excess amounts of fatty, sweet and protein foods. The drinking regime remains normal. The day before it is necessary to avoid stressful loads and intense sports. If the patient is taking any medications that affect coagulogram parameters, then, depending on the goals set for the study, it is necessary to either continue or stop taking them a few days before. This should be discussed with your doctor before taking the test.

If you need urgent results, you can contact the INVITRO offices, where express diagnostics are carried out. In this case, the analysis will be ready in about 2 hours.

Some of the proteins of the blood coagulation system are acute phase proteins. They are produced during stress, which includes not only physical and emotional stress, but also illness. Consequently, any persistent or short-term, but intense stress in the body can lead to changes in coagulogram parameters.

Dehydration (dehydration) is one of the reasons for blood thickening and an increase in the concentration of coagulation factors, which also leads to a distortion of the result.

The state of the blood coagulation system changes during pregnancy, both in the direction of increasing and decreasing the activity of a number of proteins.

The use of many medications affects the blood coagulation system. Thus, the first generations of oral contraceptives lead to an increased risk of thrombosis, and anticoagulants lead to bleeding. The list of drugs that affect the activity of the coagulation system is huge. When receiving any drug therapy, you should first consult with your doctor about the possible effect of a particular drug on the test result.

Taking certain medications by a pregnant woman, for example, warfarin, rifampicin, phenytoin, barbiturates, affects the production of clotting factors in the fetus. The child may subsequently be at high risk of bleeding.

Coagulogram. What is this?

You can take a coagulogram test on any day (except Saturday and Sunday) in the laboratory of the National Health Institution “Nodal Hospital at the station. Vyborg. The result is issued on the same day. (office no. 4)

Coagulogram (syn.: hemostasiogram) is a set of blood indicators that characterize its ability to clot. Blood clotting is one of many protective functions that maintain the normal functioning of the body by preventing excessive blood loss.

The coagulogram can be basic or extended. Typically, a baseline study is ordered first. It helps to understand where in the system the deviation from the norm occurred. And if a pathology is detected, a detailed study is carried out, as a result of which not only qualitative changes are determined, but also quantitative ones.

Material for taking a coagulogram: Venous blood Indications for a coagulogram:

• monitoring the state of the hemostasis system;
• routine examination before surgery;
• pregnancy;
• gestosis (complication of a normal pregnancy);
• monitoring of anticoagulation therapy; (for example, taking heparin)
• monitoring of antiplatelet therapy;
• hematological diseases;
• varicose veins Moscow
• atrial fibrillation;
• Coronary heart disease (CHD);
• stroke;
• Pulmonary embolism (PE);
• DIC syndrome; (impaired blood clotting due to massive release of thromboplastic substances from tissues)
• taking medications (oral contraceptives, glucocorticosteroids, anabolic steroids);
• cirrhosis of the liver.

Basic coagulogram parameters:

1. Fibrinogen . The most important test of the state of the coagulation system.
2. Prothrombin index (PTI), INR (international normalized ratio), PTT (prothrombin time) . Usually one of these tests is performed, based on the equipment available in the laboratory. The most universal test is INR. All of these studies show an extrinsic clotting pathway.
3. Activated partial thromboplastin time . In the test you can find the abbreviation APTT.
4. Thrombin time.

Additional coagulogram parameters:

• Protein C. An insufficient amount of this parameter leads to thrombosis.
• Antithrombin . Like protein C, it is a factor in the anticoagulation system.
• D-dimer . Formed as a result of the destruction of a blood clot.
• Lupus anticoagulant.
• Plasma tolerance to heparin.
• AVR (Activated Recalcification Time).
• RFMC (soluble fibrin-monomer complexes).
• Plasma recalcification time.

Coagulogram norms (Table):

Preparing for a coagulogram:

• This analysis is carried out in vitro (in vitro - outside the body). Blood is taken from a vein.
• Blood is donated on an empty stomach. The last meal should be no later than 8-12 hours before the test.
• You cannot drink any drinks (coffee, tea, and especially alcohol). Only clean water is allowed.
• When taking a coagulogram, it is necessary to indicate the medications you are taking - especially those that affect the blood clotting process Moscow
• The emotional state of the patient is very important. You need to try not to be nervous, to be calm and balanced. Muscle overstrain also negatively affects the results of the study.
• It is useful to drink an additional glass of cold water right before taking the test.
• Interpretation of the results is carried out only (!) by a specialist.

Coagulogram during menstruation:

A coagulogram during menstruation is not able to give clear results. The fact is that during this period the blood is diluted and it is not possible to test its clotting abilities. Therefore, to carry out the procedure, it is advisable to wait until the end of the critical days, but not to take the test immediately.

During this period, the body, on the contrary, is interested in removing excess blood from the uterus, so coagulation is somehow impaired. After the critical days, everything returns to full normality, and the woman can easily get tested. Again, it is also not worth carrying out the procedure just before your period; the body is preparing for the withdrawal process and the blood gradually thins out. In this case, the coagulogram will be unreliable and will have to be taken again

Factors influencing the result of a coagulogram?

Factors distorting the result of the analysis:

• violation of the technique of taking and storing material;
• blood sample hemolysis;
• the presence of fat drops in the material;
• ingress of tissue thromboplastin from the patient’s capillary blood;
• the presence of a lupus anticoagulant in the patient’s blood (directly inhibits coagulation factors);
• sharply increased or decreased hematocrit;
• anticoagulants entering the blood sample;
• transfusion of donor blood components in the last month (distorts the fibrinogen indicator, APTT).

Factors that increase INR and PT and reduce PI:

• drinking alcohol, fatty foods;
• medications: antibiotics, anabolic steroids, aspirin (in large doses), acetaminophen, allopurinol, warfarin, vitamin A, heparin, glucagon, diuretics, MAO inhibitors, indomethacin, kanamycin, clofibrate, corticotropin, levothyroxine, mercaptopurine, methyldopa, mefenamic acid, mithramycin, nalidixic acid, neomycin, nortriptyline, propylthiouracil, reserpine, streptomycin, sulfonamides, tamoxifen, tetracyclines, tolbutamide, phenylbutazone, phenytoin, quinidine, quinine, chloral hydrate, chloramphenicol, cholestyramine, cimetidine, ethanol.

Factors that reduce INR and PT and increase PI:

• excess intake of vitamin K from food (found in beef or pork liver, green tea, broccoli, chickpeas, cabbage, turnips, soy, green leafy vegetables);
• diarrhea and vomiting (due to dehydration and increased blood viscosity);
• medications: vikasol (vitamin K analogue), antacids, antihistamines, ascorbic acid, barbiturates, griseofulvin, digitalis, diuretics, colchicine, corticosteroids, caffeine, xanthines, meprobamate, oral contraceptives, rifampicin, theophylline, phenobarbital, chloral hydrate.

Factors that increase APTT:

• antibiotics, asparaginase, aspirin, warfarin, heparin, thrombolytic drugs (streptokinase, urokinase), quinine, cholestyramine, cyclophosphamide, enoxaparin.

Factors that increase fibrinogen content:

• estrogens, oral contraceptives.

Drugs that reduce fibrinogen levels:

• atenolol, valproic acid, lipid-lowering drugs, corticosteroids, progesterone, thrombolytic drugs (streptokinase, urokinase), fluorouracil, estrogens, fibrin degradation products, nicotine.

Coagulogram (screening)

No. OBS103Comprehensive studies

Hemostasiogram (coagulogram), screening A basic set of tests used for screening assessment of the state of the blood coagulation system.

Up to 1 business day

RUB 1,360 Add to cart

No. OBS109Comprehensive studies

Hemostasiogram (coagulogram) extended This set of tests is used for a detailed assessment of hemostasis disorders: if thrombophilia is suspected, the risk of developing thromboembolism and/or disseminated intravascular coagulation (DIC), or the patient’s severe general condition.

Up to 1 business day

RUB 3,790 Add to cart

You can take a coalogram at the nearest INVITRO medical office. A list of offices where biomaterial is accepted for laboratory research is presented in the “Addresses” section.

The blood coagulation system is primarily an enzymatic system that provides external, internal and general coagulation pathways. These mechanisms are successively replaced, but they can also occur independently of each other.

The screening coagulogram includes the following indicators:

• prothrombin (prothrombin time, prothrombin (according to Quick), INR - international normalized ratio);
• fibrinogen;
• APTT (activated partial thromboplastin time);
• thrombin time.

These indicators are basic and allow you to evaluate all coagulation pathways.

Research method and norm of blood test for prothrombin

Research method:

clotting (to activate the coagulation cascade, the plasma is incubated with the optimal amount of thromboplastin and calcium. After this, clotting time is measured).

Units:

Prothrombin time – seconds. Prothrombin index - %. INR is a calculated value expressed as a number close to 1.0 (0.85-1.15).

Expected values_Sysmex CA 660:

9.9–11.8 s / 70–130% according to Kwik.

Normal indicators

Preparing for a prothrombin time test

There are special rules for taking medications for patients undergoing therapy with indirect anticoagulants. These drugs are vitamin K antagonists (warfarin). In this regard, in addition to special rules for taking the drug, therapy should be accompanied by constant monitoring of prothrombin and INR. Before the start of the study, the full daily dose of the drug is taken at a time (it is advisable that the dose be taken between 16:00 and 17:00, unless the attending physician recommends a different regimen). It is important to maintain a strict, uniform time interval from the moment of taking the drug and collecting the material. It is preferable to donate blood for testing in the morning on an empty stomach. It is recommended to stop eating 8-14 hours before the start of the study. At the same time, drinking a small amount of water is allowed. In exceptional cases, the test can be taken 4-5 hours after eating a small amount of light food (but not later). On the eve of the study, any active physical exercise, consumption of alcoholic beverages, as well as increased psycho-emotional stress should be excluded.

Decoding the result

I. Quick's prothrombin, prothrombin time, and international normalized ratio (INR) reflect the activity of the extrinsic coagulation pathway.

• Prothrombin time
  is the time of blood clotting after the addition of substances (thromboplastin with calcium) to the plasma that trigger the extrinsic blood coagulation pathway. Time is measured in seconds (sec.). The longer the prothrombin time, the lower the activity of coagulation factors.
• Prothrombin according to Quick
  is considered a more objective indicator of the external pathway, since during the analysis the clotting time is studied depending on the different concentration of coagulation factors in the blood obtained by diluting the test material in the laboratory. The indicator is measured as a percentage (%). The longer blood clotting occurs, the lower the Quick prothrombin percentage.
• The international normalized ratio (INR)
  is a prothrombin test standardized in accordance with international recommendations. It is calculated using a certain formula. The higher the INR, the longer it takes for a blood clot to form.

Prothrombin time, prothrombin according to Quick and INR with normal fibrinogen content and activity also reflect the activity of the prothrombin complex (II, V, VII, X blood coagulation factors).
When prescribing therapy with anticoagulants from the group of vitamin K antagonists (warfarin), there is an increase in INR and prothrombin time and a decrease in prothrombin according to Quick. Other causes of these changes may be vitamin K deficiency (for example, with hemorrhagic disease of the newborn), hereditary deficiency of factors II, V, VII, X, liver and intestinal diseases. The opposite picture, i.e., a decrease in INR, a decrease in prothrombin time and an increase in prothrombin according to Quick, occurs in conditions accompanied by increased blood clotting: thrombosis, blood thickening during dehydration, when taking oral contraceptives, barbiturates.

II. Activated partial thromboplastin time (aPTT)

with normal content and activity of fibrinogen, it characterizes the internal pathway of blood coagulation, which includes the activity of factors II, V, VIII, IX, X, XI, XII. APTT is determined by adding reagents that trigger this clotting pathway to a blood sample and measuring the time it takes for the blood to form a clot. Measured in seconds (sec.). The slower the blood clotting, the longer the APTT.

This indicator is used to monitor therapy with heparin (direct anticoagulant), and an increase in the aPTT value is noted. Other causes of increased time include hereditary and acquired deficiencies of intrinsic pathway coagulation factors, for example, in hemophilia, hemorrhagic disease of the newborn, liver and intestinal diseases, some autoimmune diseases, etc. The reasons for increased aPTT are the same as for Quick's prothrombin.

III. Thrombin time and fibrinogen reflect the overall, or final, pathway of blood clotting.

• Fibrinogen
  is blood clotting factor I, a protein synthesized in the liver and converted into fibrin, the basis of the clot during blood clotting. It is also an acute phase protein. It is measured in grams per liter (g/l). With increased thrombus formation and various inflammatory diseases, the synthesis of this protein increases. In case of liver diseases, hereditary fibrinogen deficiency, etc., its concentration decreases.
• Thrombin time
  is the blood clotting time necessary for the formation of a fibrin clot when thrombin is added to the plasma - an enzyme (factor IIa), which appears when blood coagulation factors interact when a vessel is damaged. Thrombin time depends on the level and activity of fibrinogen. Measured in seconds (sec.).

Changes in thrombin time generally correlate with fibrinogen levels. However, with such a hereditary disease as dysfibrinogenemia, i.e., a violation of the functional activity of fibrinogen, an increase in thrombin time and a coagulation disorder occurs, despite the normal amount of fibrinogen in the blood.

Description of the blood test for prothrombin

Prothrombin is factor II of the blood coagulation system.
Prothrombin time is a specialized coagulation test. Using it, you can determine the plasma clotting time, which starts from the moment of adding tissue thromboplastin, as well as calcium. This test clearly shows the state of the external blood clotting pathways. In addition, it can be used to determine the degree of activity of the prothrombin complex, namely factors II, V, VII and X. The results of the test are displayed in the form of an international normalized ratio (INR). INR is the ratio of the prothrombin time of the test plasma and the normal mean prothrombin time.

It is the prothrombin time that can currently be considered the basis for assessing the state of the blood coagulation system.

Prothrombin time is a specialized coagulation test. It can be used to quickly and efficiently evaluate the extrinsic coagulation pathways. The main indicators that are “derived” are the international normalized ratio (INR) and the prothrombin index according to Quick. Together they are a clear indicator of prothrombin time.

Thanks to studies using prothrombin time, a specialist is able to monitor changes in the condition of patients during therapy with the use of indirect anticoagulants. Thus, the ability to respond in a timely manner to changes in conditions that may cause bleeding is significantly increased.

The same analysis can be used to detect the activity of factor VII. It is worth considering that only a specialist can make the correct diagnosis, accurately interpret the test results, and determine the treatment method.

Test material:

Plasma (anticoagulant - sodium citrate).