International normalized ratio (INR). What is an INR blood test? Multi-decoding is normal for adults

Blood test for INR or international normalized ratio is a test that is done in combination with other tests, such as prothrombin time (PTT) or partial thromboplastin time (APTT). The main reason for conducting them is assessment.

But the results of the PTT test are highly dependent on the reagents added to the blood sample and the methods for determining the final indicators. This is the disadvantage of this test. This is why the INR test is most often performed abroad: it solves this problem by giving the same standardized result, regardless of the reagents and other things.

Reasons for the analysis

Plasma INR can be performed on a regular basis. This occurs when testing the effectiveness of a treatment for poor blood clotting. This test is also performed to identify signs of low clotting. These include: frequent bleeding from the nose, heavy blood loss during menstrual cycles, bleeding gums, bleeding after injury and the like. This test is very important to get before surgery to know about the likelihood of blood clots or significant blood loss.

Preparing for the test

Before the blood test, you will have to fast for eight hours. Also, if you are taking any medications, especially antibiotics, tell your doctor. He or she may advise you to change your medication regimen or stop taking it on the day of the test.

Procedure

Blood is taken from a vein with a syringe, then placed in test tubes with a special liquid and tested for INR.

Norms

The normal test result is 0.85–1.25. More high performance indicate illness or recent surgery.

A high INR level indicates the risk of bleeding, and a low level indicates the risk of blood clots.

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PTI and INR blood test - what is it and why is it necessary? A blood test is performed in case of diagnosis serious illnesses, in particular during the formation of blood clots. There is a certain series of studies that will characterize blood clots and promptly identify the disease.

If the blood vessels are not normal, diseases such as thromboembolism, thrombophlebitis and thrombosis may occur. If blood clots form in the vessels, then you can expect the most negative consequence. This often leads to myocardial infarction. Oral anticoagulants can normalize blood clotting and avoid terrible illnesses.

Oral anticoagulants are special medications that can reduce excessive blood clotting and thereby block the possibility of blood clots in the blood vessels. Today, these drugs are used not only as treatment, but also as prevention of thromboembolism, venous and arterial thrombosis.

The main composition of such anticoagulants is the content of vitamin K, which has vegetable origin and is found in foods such as broccoli, green tea leaves, spinach, lettuce, raw cabbage, raw chard, endive, beans, green onions, soybean oil, red lettuce and more.

However, all of the above refers to prevention rather than diagnosis. If there is concern or risk of diseases associated with blood clots in the vessels, or if the blood clotting system is impaired, then it is necessary to perform a coagulogram. In more detail, a coagulogram is a whole set of blood tests, which ultimately has different indicators. One of the most important and decisive such indicators is PTI. The abbreviation stands for prothrombin index. A healthy person has PTI indicators as close as possible to 100%. If a person suffers from diseases associated with blood clots, then the PTI rate should be at least 30%. Otherwise, the patient has a huge risk of heart attack, stroke and other diseases. Therefore, determining the level of blood function is extremely necessary.

A coagulogram may also have another name - hemostasiogram. The analysis itself can be general or detailed. General analysis implies the entire survey base and answers main question: is there a pathology and in what system does the deviation from the norm occur? If there is a violation, a detailed diagnosis is carried out.

1. Pregnancy. The analysis is carried out once every three months, and much more often if gestosis is detected. During pregnancy there can be both positive and negative processes in the body. expectant mother. For example, fetoplacental insufficiency is common.
2. Scheduled operations. With any surgery, the patient loses blood, so it is important for doctors to evaluate whether a person's blood is clotting prematurely.
3. Leech therapy, otherwise called hirudotherapy. The analysis is necessary in order to prevent hemorrhages.
4. Any disorders caused by blood clotting.
5. Liver diseases.
6. Cardiovascular pathology. This includes experienced and suspected stroke, heart attack, and coronary artery disease.
7. Autoimmune disorder.
8. Vascular pathologies: varicose veins, increased thrombosis.
9. Selection of drugs that contain acetylsalicylic acid.
10. Use or prescription of contraceptive medications. In this situation, the analysis will be performed once every 3 months.
11. Prescription of anticoagulants.

A coagulogram involves performing tests such as PTI and INR. Let's look at each of them in more detail.

What is PTI?

Blood in the human body must be liquid. In this way she will be able to perform vital important functions in organism:

• protection against infections;
• maintaining body temperature;
• supply of all necessary nutrients;
• blood transportation.

At various wounds the person may lose blood. Thanks to the normalized function of blood clotting, a blood clot forms on the injury, which saves from life-threatening blood loss.

A special protein called prothrombin is responsible for the creation of such blood clots in injuries. PTI analysis helps determine its condition. The main task of IPT is to determine the percentage of the required time for blood plasma clotting to the clotting period of the final plasma.

How to decipher PTI indicators

As a result of the study, three conclusions can be drawn:

1. The condition is normalized.
2. Hypocoagulation.
3. Hypercoagulation.

The normalized state of a person shows 90-100%. The sensitivity of the body and the drugs used have an influence.

Hypocoagulation is the body’s tendency to experience severe blood loss and clotting is impaired. Occurs in case of low prothrombin index. There can be many reasons:

• the patient uses drugs that affect blood clotting;
• excess vitamin K;
• lack of fibrinogen;
• genetic pathologies;
• liver function is impaired.

Hypercoagulation – increased blood clotting. It is determined when the PTI significantly exceeds the norm. The reason may be:

• oncological diseases;
• heparin;
• use of anticoagulants;
• long-term use of hormonal contraceptives;
• influence nicotinic acid, quinine, laxatives, anabolic steroids;
• use of antibiotics;
• liver dysfunction resulting from nephrotic syndrome and chronic diseases;
• genetic characteristics of the organism.

Pregnancy and prothrombin index

PTI is important procedure during pregnancy. A woman's prothrombin index percentage will help prevent severe blood loss during childbirth. If an abnormal condition is detected, the patient is prescribed appropriate medications that can easily solve the problem.

Some women do not feel the need to undergo this test, but it is very important. It is due to blood loss that most often deaths occur during childbirth.

The prothrombin index has always been considered a very important procedure, but nevertheless it has some inaccuracies. An INR analysis can tell you more about blood clotting.

What is an INR analysis?

INR, which stands for international normalized ratio, determines PT, which stands for prothrombin time.

In other words, this analysis will accurately show the situation of blood clotting, which will provide narrower and more accurate control. PT is indicated in seconds. For example, if warfarin is used as a drug, it is imperative to determine the INR.

Interpretation of INR results

When conducting this analysis, no laboratory conditions can affect the result, so the INR will calculate the coagulation factor of certain proteins in the plasma without error. The norm may vary among patients. It directly depends on what drugs and what form of treatment the patient undergoes.

For example, a normal indicator can be from 0.8 to 4%. If the result is higher or lower than this parameter, then this is a reason to seriously think about it.

Elevated INR values ​​indicate low blood clotting. As a result, they may open internal bleeding. If the international normalized ratio is above 5.5%, then the patient must be urgently hospitalized.

If the INR level in a blood test is low, this indicates:

• vitamin K deficiency;
• during pregnancy - about hypercoagulation;
• in case of injury or necrosis, too much may enter the bloodstream a large number of tissue thromboplastin;
• prothrombin deficiency, which occurs as an acquired pathology or is inherited genetically.

The international normalized ratio will give detailed description about the state of human blood. In addition, it will indicate the patient’s tendency to thrombosis before surgery, predict external and internal bleeding and help the doctor prescribe the correct treatment as quickly as possible.

The patient should not have any problems with the place where these tests are taken, since IPT and INR are done in every hospital, laboratory and clinic. The turnaround time is usually about 3 days. In more expensive institutions, IPT or INR can be done in a very short time. For example, you can pick up the result the very next day.

It has already been said above that the analysis results cannot have laboratory errors. Therefore, the indicator indicated on the final sheet is reliable result. But there are a few tips that you should listen to before taking the test:

1. If you are taking warfarin, you must take it at the same time every day.
2. It is best to always take tests for PTI and INR in the same laboratory.
3. It is also recommended to donate blood at the same time, with a maximum error of 2 hours.

Such simple tips will help you get a reliable answer. In addition, as a preventive measure and to support circulatory functions, it is recommended to eat as much greenery as possible.

A value used for the purpose of obtaining a comprehensive assessment of the patient's circulatory system, and also obtained strictly using mathematical calculations, is called the international normalized blood ratio. Now you know what blood INR is - this is the ratio between the standard prothrombin time and the corresponding time of each person, and this ratio is raised to the power of the ISI coefficient (ISI - international thromboplastin sensitivity index).

INR norms

INR is necessary to indicate compliance with the norm of the above prothrombin(PTI) in the blood, which must be donated for research. Why do a blood INR test, what is the norm? This analysis has standards that constitute values ​​for healthy adults. In the case when medications of this group are taken, the norm may differ significantly.

In healthy people, the optimal INR ranges from 0.8 to 1.2.

A blood test to calculate INR is prescribed in certain cases, and the norms for the characteristics may vary in each case.

The value of this indicator is especially important when assessing the activity of the blood coagulation system.

Changes in the condition of the subject can be judged taking into account the changes occurring. Only a highly qualified doctor can decipher.

Elevated INR

An elevated level usually indicates the development of certain pathological processes. An increase may occur due to the use of antibiotics such as Blémarin, Diclofenac. The reason in this case is synthetic hormones thyroid and anabolic steroids. It is necessary to donate blood repeatedly to monitor changes in the body.

INR above 1.5

In accordance with the standards, a person whose INR value is more than 1.25 conventional units (provided there are no blood thinning drugs in the blood) has a risk of developing the following pathologies:

INR above 6

If readings are more than 6 units, immediate treatment is required. In this case, an increased international normalized blood ratio indicates a high probability of bleeding in various locations with different intensity, which is very dangerous for such diseases:

• ulcerative or inflammatory pathologies of the intestines, stomach;
• essential hypertension (hypertension);
• cerebrovascular diseases;
• various kidney diseases.

Readings exceeding the norm indicate negative changes in the patient’s blood coagulation system, which is also reflected in the coagulogram.

Low INR

When the INR is low, you should start looking for the reasons for this phenomenon, they can be different:

A low indicator is a prerequisite for carrying out repeated or additional research.

It is especially important to monitor blood counts regularly, efficiently and in a timely manner. A low INR may require urgent treatment.

The doctors you contact should have extensive experience in working with a variety of heart diseases and be able to provide highly qualified care. It would be a good idea to require certificates as proof.

INR during pregnancy

During pregnancy, it is especially important to determine the INR, since at this moment female body undergoes a large number of changes, a new, uterine-planetary 3rd circle of blood circulation appears. Because of this, the INR of pregnant women increases significantly, while its value remains within the normal range, but quite close to its upper limit.

The INR norm when taking warfarin is determined individually for each patient. Doctor A. Chirkova talks about this study.

International Normalized Ratio (INR)

Blood clotting in Russia is determined by a blood coagulogram test. Among other indicators of the coagulation test, INR is also examined. This test compares a patient's blood clotting ability with a standard sample. Normal INR is 0.8-1.2, the average value is 1.0.

The lower the INR value, the higher the blood clotting ability. The higher the INR value, the less clotting. The INR indicator is determined in patients who are being treated indirect anticoagulants– coumarins, including warfarin.

The INR indicator has been adopted since 1983 as a single symbol throughout the world. INR (INR - International Normal Ratio) is an independent test that can be determined independently of the coagulogram.

INR levels are monitored at least once a week. While the patient is in the hospital, the test can be taken up to 5 times. When the situation returns to normal and the INR level becomes more or less stable, the norm is monitored once every two weeks, but not less often. This is explained by the fact that the coagulability index can change even with stable dosage warfarin. The body's sensitivity to the action of a drug depends on many internal and external factors, for example, from:

• Diet and daily menu;
• Physical activity;
• The presence of chronic diseases and their nature;
• States liver tissue and kidney function.

The standard mode of monitoring the INR norm is changed to more frequent checks in such cases as:

• Influenza, cold or infectious inflammation requiring additional treatment;
• Moving to another place of residence with a change in climate;
• Significant change in usual diet;
• Lifestyle changes.

This blood test is probably the most common in the world, with more than 900 million determinations per year.

For patients, the need to visit the laboratory every week turns into many years of hard labor, so manufacturers of laboratory tests have released express INR tests that can be used even at home

Treatment with warfarin

Warfarin is prescribed for treatment and prevention

• venous thrombosis and pulmonary thromboembolism.
• stroke and thromboembolism
• heart valve replacement
• after myocardial infarction
• at rheumatic lesions heart valve disease
• with cardiac anomalies (with an open foramen ovale)
• in case of impaired contractile function of the left ventricle
• antiphospholipid syndrome

Long-term use of warfarin may be accompanied by various side effects Therefore, it is important for the doctor to constantly keep the situation under control and monitor the patient’s normal condition in order to change or stop taking the drug in time.

Not all patients can adapt to taking warfarin. No matter what they tell you, if you feel unwell, be sure to ask your doctor to change your medication.

Warfarin is not always taken for life; in some diseases it is discontinued after 4-6 months. Sometimes warfarin is replaced with alternative drugs Pradaxa, Xarelto and others.

Method of monitoring blood clotting during warfarin treatment

Taking anticoagulants creates a situation where the patient is between two fires. Specifically, between overdose and underdose of warfarin. Both conditions do not bode well. Too much can cause bleeding, and too little can cause the formation of dangerous blood clots. When taking heparin, the patient is regularly examined for a coagulogram; when taking warfarin, the international normalized ratio is determined. This test can be done separately from the coagulogram.

In order not to cross safety boundaries and maintain the INR within the required limits, constant monitoring of the level of blood clotting is necessary. It is important to take into account that normal value INR at various diseases will differ from the indicators of a healthy person, which range from 0.9 to 1.2.

When taking warfarin, the concept of “Target range” is accepted - this is the individual INR value that is optimal for a particular patient. The target range is determined not only by the disease, but also by risk factors for thrombosis. For the same disease, the target range will vary between patients. One may have 2.5 and another 4.0.

Below are very conditional boundaries that must be adhered to:

• when taking warfrin and atrial fibrillation, the conditional INR norm is 2.0 – 3.0;
• for chronic atrial fibrillation, the conditional norm is 2.2 – 3.1;
• after implantation of the valve, it is necessary to maintain the numbers at 2.6 - 3.5.

In general, as a doctor and as a user of anticoagulants, I can wholeheartedly feel sorry for us who need warfarin. I don’t know of a more unpleasant drug with which you constantly have to be on guard.

How often should I measure INR?

At the very beginning of taking warfarin, the INR will have to be measured every 2-3 days. Next, when the dose of warfarin is selected, we switch to the regimen of 1 determination per week. If the patient has undergone coagulation measurements three times and they are within the specified interval, then you can switch to measuring once every 2 weeks. However, many people ignore this rule, and as a result they experience complications: I have seen patients receiving warfarin with an INR of 20.

What if the test is less than the target value?

Is your INR less than the norm determined by your doctor? This means that blood clotting has increased and you are at risk of thrombosis. You should consult your doctor; the dose may need to be adjusted.

What to do if the test is higher than the target value?

This is not good, if the INR exceeds your norm, you are at risk! The likelihood of complications and bleeding has increased. Most likely, the dose of warfarin will have to be reduced. Consult your doctor. If you are using a home device and you measure the numbers, read what to do in the article about warfarin overdose and seek medical help immediately.

Sometimes the patient cannot stay within the target range. This happens when you change your diet. Greens and salads containing vitamin K affect the INR by lowering it (clotting increases), the risk of thrombosis increases.

Taking certain medications may change test values. Taking aspirin and voltaren is contraindicated, but by mistake the patient can break this rule, and the risk of bleeding increases. About 300 drugs increase the test result, and more than 100, on the contrary, decrease it. Be careful! If you cannot keep the INR within normal limits, do the test more often and adjust the dose by adding or reducing the dosage by ¼ tablet.

Your INR is within the normal range does not mean you can stop checking it. The determination should be regular at least once every 2 weeks. If bruises suddenly appear on your body, your nose bleeds, or you see black stool, you should immediately do a test and consult a doctor.

A competent doctor will always tell you in detail what your target range is and how to achieve it.