PTI blood test: what is it, the norm, explanation. Let's understand what a PTI blood test is? What does PTV mean in biochemistry?

The PTI (prothrombin index) and INR (international standardized ratio) allow us to draw conclusions about whether the blood clotting system is functioning well or poorly. Such knowledge is necessary during surgical interventions, to control drug therapy in the treatment of pathologies of the cardiovascular system and their prevention.

What the study shows on PTI and INR

Blood is the main substance of the body. All processes occurring at the cellular level, and, therefore, the normal functioning of each organ depend on its quality. One of the most important characteristics of blood is its viscosity.

The optimal consistency of blood in the body is ensured by the coordinated work of two systems:

• Coagulation regulates thrombus formation, which is necessary to stop bleeding when the vessel wall is damaged.
• The anticoagulant keeps the blood fluid. Its main function is to prevent spontaneous thrombus formation.
• If the balance between them is disturbed, the person suffers from bleeding or the formation of thrombi (blood clots).
• To assess the functioning of the blood coagulation system, a comprehensive study is carried out - a coagulogram. Its indicators make it possible to predict how childbirth or surgery will go.

Plasma factors have the main influence on blood clotting. The most important of these is prothrombin (factor II). This complex protein is a precursor to thrombin. It is he who is responsible for the formation of a blood clot. Protein is produced by the liver, which requires vitamin K.

Based on the results of the prothrombin analysis, the following is assessed:

• functioning of the digestive system (especially the liver)
• risk of having a stroke or heart attack
• K level in the body
• danger of blood clots with varicose veins
• effectiveness of anticoagulants

PTI is the percentage ratio of the clotting time of standard plasma (PTT) to similar indicators of the patient’s blood.

Depending on the sensitivity of the reagents used (tissue factor), results may vary significantly. In this regard, regular blood tests for PTI are recommended to be performed in the same laboratory.

To minimize the dependence of the test result on laboratory conditions, the World Health Organization introduced the INR (International Standardized Ratio) indicator into clinical practice in 1983.

When processing data obtained as a result of research, the sensitivity of the reagent (MIS) is taken into account, the index of which must be indicated by the manufacturer on the packaging. It is different for each batch of tissue factor. Its value can range from 1.0 to 2.0.

The INR indicator is the ratio of the patient's blood PTT to the standard PTT, raised to the value of the sensitivity index of the reagent used. Such measures significantly reduced the dependence of the analysis result on the type of tissue factor, but did not completely eliminate it. Therefore, periodic blood tests for INR are also recommended to be performed in one laboratory.

Who needs a prothrombin test?

People with vascular pathologies are often prescribed anticoagulants as prevention and treatment. These drugs reduce blood clotting, preventing the formation of blood clots.

To monitor the rate at which a clot forms while taking such medications, blood is periodically taken from the patient to be tested for PTI and INR. Based on the results of the analysis, the dosage of the drug is adjusted for each individual person.

Monitoring the prothrombin index is necessary for people diagnosed with the following diseases:

• cirrhosis of the liver
• oncology
• thromboembolism
• hepatitis
• hereditary diseases of the blood coagulation system
• pathologies of the cardiovascular system (angina pectoris, arrhythmia, atherosclerosis)
• gynecological diseases
• diseases of the gastrointestinal tract (colitis, enterocolitis), in which there is a deficiency of vitamin K

It is mandatory to study PTI indicators in people with an artificial heart valve and in patients who have suffered a stroke or myocardial infarction. Monitoring the prothrombin index is necessary when taking certain hormonal drugs.

A test for PTI or INR is performed in the laboratory on the direction of the attending physician. Venous blood is most often used for research. The test is taken in the morning on an empty stomach. Food intake is stopped 10 hours before blood sampling.

It is necessary to temporarily give up smoking, tea, coffee and alcohol. Before drawing blood, it is recommended to drink a glass of water (clean). You should tell your doctor about using oral contraceptives or other medications. Stress hormones can distort the test results, so it is advisable not to be nervous on the eve of donating blood for testing.

You can monitor the prothrombin index at home. To do this, you need to purchase a special device. Fresh blood is applied to a test strip, which is then inserted into the device. The INR value is displayed on the display. Blood for analysis is taken from a finger. The puncture is carried out by an automatic device.

Norm of PTI and INR indicators

The PTI indicator is considered normal if it is in the range from 70 to 100 units. When taking medications that reduce blood clotting, the PTI indicator decreases. With such therapy, its drop to 24.0 - 42.6 units does not cause concern.

A higher value increases the risk of vascular pathologies (heart attack), which forces you to increase the dose of anticoagulants. At lower levels, there is a risk of bleeding, both internal and external. In such a situation, the dosage of Warfarin is reduced.

The results of a blood test for prothrombin can be presented in the INR form. Its indicators are more stable, as they do not depend on laboratory conditions. When choosing between two forms of research, most specialists prefer the internationally standardized ratio.

The INR rate ranges from 0.85 to 1.25. An increase in values ​​to 2.0 - 3.0 is considered normal when using Warfarin, treating pulmonary embolism or venous thrombosis, or heart valve defects. Vascular diseases increase the INR to 3.0 - 4.5, which is also considered normal for this pathology.

An increase in the INR value in patients not taking Warfarin or its analogues may indicate the development of a number of pathologies:

• malignant tumors
• pre-infarction state
• polycythemia
• reflux of bile into the duodenum
• disruption of lipid absorption
• illnesses
• hemorrhagic disease in newborns

An increase in INR to 6 units or higher requires immediate hospitalization. This condition is especially dangerous for people with kidney pathologies, inflammation or peptic ulcers of the gastrointestinal tract, and arterial hypertension. These patients have a significantly increased risk of internal bleeding.

If the INR is below normal, this may indicate the following disorders in the body:

• vitamin K deficiency
• prothrombin deficiency (congenital or acquired)
• increased levels of tissue thromboplastin in the blood
• vascular thrombosis
• activation of fibrinolysis (with excessive physical activity, stress, pain)

A low INR indicates the risk of blood clots, which can cause thrombosis of the pulmonary arteries and veins of the lower extremities, myocardial infarction or stroke.

While watching the video you will learn why INR is needed.

The body increases blood clotting during pregnancy to prevent it during childbirth. This is a normal process. Determination of PTI is necessary in the treatment and prevention of a number of serious pathologies of the body. Sometimes such research helps save a person's life.

Prothrombin index (PTI) is one of the most important laboratory tests that characterizes the state of the coagulation system. It is expressed as a percentage. For various conditions, an analysis for PTI is prescribed. The norm in healthy people is 95-105%.

It is carried out in two directions - internal and external paths. The PTI value reflects precisely the external coagulation pathway.

What is prothrombin?

The formation of blood clots and thrombi occurs under the influence of a special protein - thrombin, which, under the influence of certain biochemical processes, is converted from prothrombin. Thus, the protein prothrombin is the second blood coagulation factor. It is synthesized with the participation of vitamin K in the liver.

The prothrombin index (according to Quick) allows you to determine the activity of prothrombin. This test is calculated as a percentage of the patient's blood plasma readings compared to the control sample. To monitor the functioning of the coagulation system, a blood test for PTI is prescribed. The norm in different laboratories may differ slightly, but these differences are not significant. They depend on the reagents the laboratory works with. In some conditions, for example, with varicose veins, heart attacks or after heart surgery, the doctor sets the norms for patients, because in these cases, it is necessary to achieve blood hypocoagulation (reduce blood clotting). This is done to prevent blood clots.

Who should be tested for PTI?

Usually, when studying PTI, the norm in women is the same as in men. This indicator changes only during pregnancy, and there are a number of reasons for this, which we will talk about a little later. In what cases is a biochemical blood test IPT prescribed? The norm of this study, for example, when taking indirect anticoagulants, may be two times lower. Patients taking such drugs should regularly monitor IPT and INR. Testing for PTI is mandatory in the following situations:

• Before any operations.
• People taking anticoagulant medications to prevent blood clots.
• Women during pregnancy.
• People suffering from diseases of the coagulation system, for example, varicose veins.
• For autoimmune disorders.
• For atherosclerosis and heart disease.
• For liver pathologies, for example, cirrhosis.
• With vitamin K deficiency.
• With antiphospholipid syndrome.
• For screening testing of the coagulation system.

During pregnancy, it is mandatory to take an IPT test. The norm for women during pregnancy is slightly higher than for other healthy people. This is due to changes in hormonal levels and the appearance of an additional uteroplacental circulation.

During pregnancy, all women are required to undergo a coagulation test. It includes:

1. PTI (prothrombin index).
2. Fibrinogen.

All these parameters are extremely important. Thus, an increase in PTI in the last stages of pregnancy to 150% or higher may indicate the risk of placental abruption. And if this indicator decreases before childbirth below 80%, there is a risk of bleeding during childbirth or in the postpartum period. Thus, it is especially important to evaluate the coagulation system late in pregnancy. To do this, a PTI analysis is performed. The norm of this indicator during pregnancy varies from 90 to 120%.

What does an increase in PTI indicate?

So, we found out that when the blood thickens, the PTI value increases. The norm of this indicator in healthy people ranges from 95 to 105%. An increase in the prothrombin index may indicate the risk of developing diseases such as:

• Myocardial infarction.
• Thromboembolism.
• Polycythemia.
• Oncological diseases.
• Placental abruption in pregnant women.

What does a low PTI level indicate?

In cases of taking anticoagulants, the PTI level can drop to 45-40%. If there is a risk of blood clots, the dose of these drugs is controlled by a doctor. After increasing or decreasing the dose of the drug, an IPT test must be taken. The norm for such patients is determined by the attending physician. If the prothrombin index has decreased not while taking anticoagulants, then this may indicate, for example, vitamin K deficiency, serious diseases of the liver or gastrointestinal tract as a whole, and in pregnant women before childbirth - the risk of bleeding during labor.

What is INR?

This indicator is the standard for determining blood clotting. The INR value responds to the activity of certain blood proteins, which are These proteins are produced in the liver with the participation of vitamin K. These coagulation factors react to taking medications - indirect anticoagulants, for example, Dabigatran, Warfarin or their analogues. In this case, hypocoagulation occurs, i.e. blood clotting occurs much more slowly. For some patients this may be vital; many of them are forced to take anticoagulants for life.

In a coagulogram, in addition to PTI analysis, other indicators are of great importance. When prescribed to patients, IPT decreases. But the norm for PTI analysis in each laboratory may be slightly different, so a standardized test was introduced - INR. Doctors use it to monitor the blood coagulation system when patients take anticoagulants. Thus, the INR in these cases is prescribed in parallel with such an indicator as a blood test for PTI. The normal INR in healthy people ranges from 0.8 to 1.2. When taking anticoagulants, coagulability decreases, hypocoagulation occurs, and INR can increase 2-3 times the norm, for example, during heart surgery or varicose veins to prevent the formation of blood clots. If the blood becomes thicker, its coagulability increases and, accordingly, the INR decreases.

Hypocoagulation. In what situations is it necessary?

In the PTI analysis, the norm is from 95 to 100%, and the INR is from 0.8 to 1.2. Let us remind you that absolutely healthy people should have such norms. But there are situations when it is vitally important to maintain INR values ​​at high levels; accordingly, PTI values ​​will be below normal, i.e. this will be a state of hypocoagulation. This condition is achieved by taking indirect anticoagulants. Only a doctor can determine the dose of the drug. Patients who regularly take such medications should regularly undergo a blood test for INR.

• In the case of atrial fibrillation, INR values ​​should be maintained within 2.0-3.0.
• Severe condition - - also requires maintaining the INR level within 2.0-3.0.
• After heart surgery, it is necessary to take anticoagulants, while in the case of aortic valve replacement, INR numbers must be maintained within the appropriate range of 2.0-3.0, and in case of prosthetics - at the level of 2.5-3.5.
• For some heart valve defects (mitral or aortic valve disease) and to prevent thromboembolism, the level of this indicator should be in the range of 2.0-3.0.
• When treating venous thrombosis, INR numbers should be 2.0-3.0.

When INR values ​​decrease below acceptable limits, the dose of Warfarin or its analogues is increased. This is done exclusively under the supervision of a doctor and laboratory tests. But an increase in hypocoagulation (increase in INR values) above the permissible corridor can also negatively affect the health of patients. This is dangerous primarily due to various bleedings. They can be either internal (uterine, gastric or intracavitary) or external, resulting from various injuries or cuts. If the INR numbers are higher than the acceptable limit indicated for a particular condition, then the dose of anticoagulants must be reduced. Some patients are forced to monitor their INR levels for life.

How to take a blood test for INR and PTI?

Blood is donated for such studies. Venous blood is taken into a test tube with an anticoagulant, which is usually sodium citrate. The ratio between the collected blood and the anticoagulant should be 9:1. The sample taken is mixed well by inverting the tube to prevent clot formation. The blood is immediately sent to the laboratory. The analysis must be performed no later than two hours after blood collection. Failure to comply with these conditions may distort the analysis result. Blood is usually donated in the morning on an empty stomach, but if necessary, this test can be done at another time using cito, i.e. urgently.

There is nothing wrong with a blood clotting test. For some disorders, it is necessary to conduct a blood test for PTI. The study is performed before surgery, childbirth or during postoperative rehabilitation. To study diseases that are characterized by blood clotting disorders, you need to perform this test.

PTI - what does it mean?

Blood clotting is the ability of blood to change from a liquid consistency to a thick one. Blood must be liquid in order to perform a number of functions in the body: transport blood and nutrients to tissues and organs, maintain body temperature conditions, and protect against infections. When internal and external tissues are injured, bleeding occurs, and at this time the clotting function manifests itself. This causes the blood to become thicker, which leads to the creation of a blood clot, which prevents large blood loss.

The development of blood clots and the transition of blood to a thick consistency is carried out with the participation of a special protein called prothrombin. It is a precursor of thrombin and has a direct effect on the formation of blood clots. Prothrombin is produced in liver tissue during the active work of vitamin K. Protein is considered the second condition for blood clotting.

Biochemical blood test for PTI ( prothrombin index) is one of the main factors of the coagulogram. A coagulogram is a profile study, with the help of which indicators of the state of the coagulation system are determined.

The prothrombin index is shown as a percentage of the amount of time for coagulation of the patient's blood plasma to the time for coagulation of control plasma.

When is the study carried out?

There are a number of diseases for which it is necessary to prescribe this biochemical blood test:

• violation of the coagulation system;
• varicose veins;
• atherosclerosis;
• liver dysfunction;
• screening of the coagulation system;
• disorders due to vitamin K deficiency;
• some of the autoimmune diseases;
• antiphospholipid syndrome;
• control of coagulation during long-term treatment with indirect anticoagulants.

Prothrombin is produced in the liver. By studying the prothrombin index, a specialist can study the condition of the patient’s gastrointestinal tract.

To minimize false deviations from normal values ​​in a blood test, you need to carefully prepare for the study. The analysis is always done on an empty stomach. If this is not possible, make sure that at least 4 hours pass between meals before analysis. If the patient is taking medications that affect coagulation, you need to inform the doctor who writes a referral for a blood test.

Where to get tested and price

Like most simple tests, this test can be done in the first available laboratory at a hospital or clinic. The deadlines depend on the institution where you will take the test. In private laboratories, the analysis result will be ready the next day, and the cost will be from 150 to 350 rubles.

Decoding and normal indicators

As a rule, the Quick method is used to determine the prothrombin index. The PTI norm during the study is within from 78% to 142%.

If the coagulation rate differs from the norm, then it is appropriate to talk about the possible occurrence of certain diseases in humans.

If the result is downgraded

A reduced PTI indicator shows a tendency to hypocoagulation (bleeding) and can occur with such pathologies as:

• Vitamin K is involved in the functioning of clotting factors. Its deficiency is observed in cases of intestinal dysfunction, as well as dysbacteriosis;
• Liver diseases. The synthesis of clotting factors is distorted. May be due to congenital factor deficiency;
• Severe acquired or inherited deficiency of fibrinogen production; severe form of DIC - syndrome - disruption of hemostasis, i.e. coagulation and clotting;
• Excessive heparin (acquired anticoagulant);
• Protein metabolism disorder – amyloidosis; kidney pathology - nephrotic syndrome;
• Types of leukemia, acute and chronic forms;
• Malignant formations in the pancreas and gall bladder;
• Chronic pancreatitis.

An indicator higher than the norm is recorded when using coumarins, acetohexamides, and antibiotics.

If the result is increased

According to the interpretation, an increased prothrombin index is a guarantee of blood clotting higher than normal, i.e. hypercoagulability. The process is observed in the following diseases:

• the first stage of thrombosis is the creation of blood clots in the veins;
• cancerous tumors;
• increased red blood cell volume – polycythemia;
• insufficiency of coagulation factors: congenital and acquired.

People taking barbiturates, oral contraceptives, corticosteroids or mercaptorunine have a high index; as well as in women in the last trimester of pregnancy.

Only an experienced medical specialist is able to make a detailed interpretation of the analysis. Diagnosticians study the blood tests that the patient has already undergone, assessing his general condition.

Prothrombin index is a very important blood indicator in the primary diagnosis of bleeding disorders. This analysis makes it possible to timely identify a person’s predisposition to conditions such as hemorrhage or thrombosis. Any violation of coagulation invariably leads to the development of life-threatening diseases. In order to identify the cause of the disease, confirm or exclude the diagnosis, patients are prescribed a test for the prothrombin index. The PTI norm in a healthy person is quite stable.

Prothrombin what is it

Prothrombin is a protein responsible for blood clotting. It is this substance that, during the coagulation chain, is converted into thrombin during injury. It forms a blood clot. Thanks to this blood clot, the wound is clogged, and the person cannot lose a large amount of blood. When the level of prothrombin increases, there is a danger of blood clots forming in the arteries, veins and vessels, and when there is a lack of it, extensive hemorrhages occur.

Every person should monitor prothrombin levels, especially after the age of 40. This will allow timely detection of violations and prevent the development of fatal diseases. According to statistics, half of the population of our planet has deviations in prothrombin levels in one direction or another. Violation causes heart attacks, strokes, thrombosis and other extremely dangerous diseases.

The biochemical PTI blood test determines the ratio of the blood clotting time of a healthy person and a patient. Using this index, doctors judge the amount of prothrombin in the blood.

The result of the analysis is indicated as a percentage.

Violations in the level of PTI are most often associated with liver diseases, because it is there that this protein is synthesized. Thus, the analysis allows not only to diagnose blood disease, but also to identify liver disease. A blood test for PTI is mandatory for people before surgery.

Normal indicators

The normal level of PTI in the blood of healthy adults ranges from 70% to 140%. However, during therapy with some medications, significant deviations can be observed, which in this case are considered normal. Also, in women, the norm of the prothrombin index may change during pregnancy, which is also not a pathology, but requires correction.

To more accurately determine the blood clotting index, today doctors use the PTI chart according to Quick. This table was created based on the blood clotting rates of healthy people in various medical institutions and therefore is a more reliable source for comparison:

What determines the change in the index?

PTI its norm depends on the level of prothrombin in the blood. If the level is below normal, there is a risk of heavy bleeding. Hemorrhages in the brain and abdominal cavity are especially dangerous. The prothrombin index may be lowered for the following reasons:

• Lack of vitamin K.
• Liver diseases.
• Lack of fibrinogen.
• DIC syndrome.
• Excess heparin.
• Amyloidosis.
• Nephrotic syndrome.
• Pancreatitis.
• Oncology of the gallbladder.
• Leukemia.
• Taking strong medications.

An increase in PTI indicates accelerated blood clotting, which can cause the formation of blood clots that can block blood flow and lead to dangerous consequences. An increased prothrombin index can be caused by the following reasons:

• Genetic predisposition.
• High content of red blood cells.
• Oncological diseases.
• Lack of heparin.
• Pregnancy in the third trimester.
• Taking certain hormonal medications.

Analysis transcript

Today, several methods are used to determine PTI. This can negatively affect the diagnosis, because indicators may differ depending on the laboratory. A blood test for PTI should be deciphered only by the attending physician, taking into account all possible factors influencing the index.

Abroad, the biochemical blood test PTI has not been used for a long time; in developed countries, another study is carried out - INR. This analysis is more accurate and its indicators have standard forms of calculation. It is for this reason that in modern clinics, instead of IPT, in our country they also conduct an INR study.

Features of female analysis

Doctors pay special attention to the level of prothrombin in the blood of women carrying a child. Every pregnant woman should donate blood for IPT so that doctors can promptly identify possible abnormalities. If deviations from the norm are detected, expectant mothers are prescribed corrective drug therapy.

Unfortunately, many expectant mothers ignore doctors' orders to get tested. They believe that these indicators are completely unimportant for their health, since they feel good. However, statistics say otherwise. According to statistics, 10% of women who did not take a blood test for PTI, unfortunately, died during childbirth from sudden severe bleeding or from the rupture of a hidden blood clot.

When should research be carried out regularly?

A PTI blood test is usually taken before surgery and during pregnancy. However, there are patients who need to have their blood tested on a regular basis to monitor the effectiveness of treatment. Such patients include:

• Patients with heart implants.
• Patients with cardiovascular diseases.
• Patients diagnosed with atherosclerosis.
• People with varicose veins.

It is very important to monitor the level of PTI in men and women over 50 years of age, because they are at a special risk group for heart and vascular diseases. Timely diagnosis in older people can save a person's life. Today, 70% of older people in our country die from heart attack and stroke. Also, the prothrombin index should be constantly monitored in patients with the following diseases:

• Thromboembolism.
• Hepatitis.
• Cirrhosis of the liver.
• Hereditary coagulation disorders.
• Oncological diseases.
• Gynecological diseases.
• Post-infarction and post-stroke condition.

In addition, PTI levels are monitored during hormonal and heparin therapy. These drugs can significantly affect coagulation. If you take these medications uncontrolled, you put your life at risk. Remember that any medicine must be taken as prescribed by a doctor, even traditional medicine.

Rules for taking the analysis

Like all blood tests, you need to donate material for research in the morning on an empty stomach. A week before the collection, you need to exclude alcohol and fatty foods from your diet. On the day of collection, you should not drink tea or coffee, and it is not recommended to smoke 30 minutes before the test. In addition, you need to try to eliminate stressful conditions; you should not be nervous. All these factors can affect the result of the analysis. If you have taken any medications, or even herbal teas, you should tell your doctor.

If abnormalities are detected, you will be prescribed additional examinations that will help determine the causes of coagulation disorders. It should be remembered that a deviation in the PTI index is not an independent disease, but only the body’s reaction to an existing disease. It is very important to identify the root cause of the deviation and undergo appropriate treatment. The attending physician must decipher the test results.

In contact with

Blood can exist in two states - liquid and thick. Liquid blood performs many functions - it protects the body from infections that enter it, transports vitamins, oxygen and necessary elements to all organs, and maintains normal body temperature. When bleeding (trauma, cut, wound of the skin) it begins to thicken, a blood clot forms, which tightens the wound.

Blood thickening is carried out using a protein - prothrombin. It is produced in the liver, and vitamin K is involved in its formation. Prothrombin is the second blood clotting factor.

Analysis of the prothrombin index (abbreviated as PTI) is an important factor in the coagulogram (a blood test that determines coagulation parameters).

The prothrombin index means the ratio of the time during which the blood plasma of the test person coagulates to the period during which the control plasma coagulates. The time ratio is measured as a percentage.

PTI is determined by different methods (according to Quick, Tugolukov). If tests are taken in different laboratories, the results may differ greatly from each other. This negatively affects the diagnosis. In many European and American countries, they use another indicator that studies prothrombin - the international normalized value (INR). The results of this study show similar results in any clinic in the world.

A coagulogram often includes tests of PTI (usually) and INR. The results of both indicators together help to recreate a holistic picture of blood clotting and prothrombin levels.