There are quite a large number of indicators characterizing the quality of functioning of the hemostatic system, and it is not always necessary to determine all of them to establish a diagnosis. But to monitor anticoagulation therapy, refusal of some may cause life-threatening thrombosis or bleeding. Such studies include a blood test for INR (international normalized ratio).
Why is determining the INR so important?
The human body has the ability to self-defense, as well as self-healing. One of the devices that provides these capabilities is the hemostasis system, which maintains the blood viscosity necessary to perform the assigned functions.
That is, it controls the clotting process, namely, when bleeding occurs, a chain starts chemical reactions aimed at creating blood clots. The latter block the flow of blood - “seal the gaps” in the vessels, as a result of which the bleeding stops.
Previously, only the prothrombin time (PTT) was checked to evaluate coagulation. This indicator indicates the time period during which fibrin filaments (high molecular weight protein) are formed, forming a blood clot that stops bleeding. An analysis was also carried out for PTI (prothrombin index), one of the derivatives of PTI.
At the same time, in various laboratories, different thromboplastins (from several manufacturers) were used to perform this blood test - reagents that specifically trigger the clotting process. This often led to different values obtained, which alarmed both doctors and patients themselves.
In order to avoid such inconsistencies, which show different results in several laboratories, and not be tied to the standards adopted in each specific one, the INR indicator was introduced. It cannot be unambiguously called analysis, since at its core it is an ordinary mathematical calculation using a standardized formula.
Reference! The test for determining INR was approved in 1983 by two International Committees - on standardization in hematology and on hemostasis and thrombosis.
The described parameter is calculated using a specially developed formula, including the PTT of the subject and the corresponding MIC coefficient, denoting the international thromboplastin sensitivity index. According to WHO recommendations, the manufacturer must determine the MRI for each batch of reagents by comparison with a generally recognized reference index.
Formula for calculating INR
The use of INR provides the opportunity to compare research results made in different laboratories and in different time without fear for the condition and life of patients. This standard coefficient, used by doctors in all countries.
Therefore, it is the result of calculating the INR that is indispensable when selecting and prescribing the dosage of anticoagulation drugs, transfusion of plasma and its components, as well as other agents. In addition, such research is necessary to determine tactics further treatment patients with diseases of the hemostatic system.
Indications for use
Most often, it is recommended to donate blood for INR along with other indicators required to evaluate different parts of the homeostasis system. This procedure indicated for the diagnosis of pathologies caused by increased thrombus formation, or, conversely, a tendency to severe bleeding. But most often it has to be prescribed to patients who are constantly taking anticoagulant drugs in order to keep the dosage of the drug under control.
Another almost equally common indication is severe liver pathologies - hepatitis and cirrhosis. Considering that the liver is an organ responsible for the secretion of many enzymes that can influence the homeostasis system, disturbances in its function certainly affect coagulation.
For patients undergoing therapy with indirect antigoagulants (most often when taking Warfarin or drugs based on it), INR analysis is prescribed regularly, sometimes even every 7-10 days. This frequency may be necessary when dosage adjustments occur due to any changes in the health status of patients with factors leading to thrombus formation. For example, deep vein thrombosis, antiphospholipid syndrome or the presence of artificial valves.
Based on this indicator, the doctor can make adjustments to anticoagulants, as well as assess the patient’s condition. Almost all recommendations for selecting the dosage of anticoagulants are determined by the results of INR and are generally accepted for different countries.
Preparation and delivery of analysis
The preparatory process for conducting an INR analysis is not labor-intensive or time-consuming, but in order to get a reliable result, it is necessary to take into account some points. Firstly, you should not donate blood after intense physical activity, physiotherapy, massage, intravenous infusions or intramuscular injections, as this may affect the indicator.
Secondly, if the patient is taking anticoagulants, then all daily dose must be consumed no later than 16.00-17.00 on the evening before the examination. We should not forget that blood for INR is given on an empty stomach, as for general or biochemical analysis, so at least 8 hours must pass after eating. At the same time, it is not correct to go hungry for more than 14 hours - this can also lead to changes in blood composition.
Normal INR values
To perform the analysis, biomaterial is taken from the cubital vein, as for most studies involving blood. Then the resulting liquid is mixed with a preservative in a test tube (usually citrate), the serum is separated from the cell mass and pure plasma is used for the diagnosis itself.
Reference! The action of citrate is aimed at binding calcium ions, which prevents blood clotting.
The laboratory then adds calcium to the serum, which neutralizes the preservative, and thromboplastin. Then the time spent on coagulation of pure serum is determined. This is PTV. Upon completion of all analytical tests, a mathematical calculation of the INR is performed. Some diagnostic laboratories use more modern methods studying the quality of coagulation, for example, this is the analysis of PTV according to Quick.
When performing it, dilution of the subject's serum biomaterial is carried out several times, and the entire procedure takes no more than one day. If the analysis result is required very quickly, then for an additional fee in some laboratories it is done and deciphered within 1-2 hours.
When anticoagulation therapy using indirect anticoagulation drugs, the patient should undergo an INR test at least once every 15-20 days. And after choosing the appropriate dosage and normalizing the patient’s condition, the analysis will be prescribed less frequently, approximately once every 6-8 weeks.
What does INR show?
This parameter is measured in units and shows a value inversely proportional to the time period of serum clotting. That is, the higher the indicator, the less prothrombin and coagulation factors. Conversely, INR decreases as prothrombin increases.
The INR level in the blood of women and men is the same and should be in the range of 0.85-1.15 units, provided that they are healthy. For patients taking indirect anaticoagulants, normal values others are 2-3 units. Medicines help slow blood clotting, making it more fluid, which prevents the formation of blood clots.
The reasons for the change in the indicator may be:
- lack of prothrombin or fibrinogen;
- taking certain medications;
- vitamin K deficiency;
- liver diseases;
- consumption coagulopathies are pathologies in which active thrombus formation occurs, causing a violation of general coagulation.
If the INR level falls below 0.5 units, then there is a high probability of risk of blood clots. This condition is usually observed when early stages thrombosis, when a large number of unclaimed coagulation factors have accumulated. In addition, the indicator often decreases in the third trimester of pregnancy, so the norm for pregnant women may be slightly changed.
Interpretation of results
Decoding the analysis will indicate the presence or absence of changes due to the quality of blood clotting, which means it will become the next step for subsequent recommendations.
High performance
If, in the course of deciphering the results of an adult healthy person, it turns out that the INR is elevated and at the same time he does not take any drugs that can affect coagulation, then we are most likely talking about pathology. It could be:
- impaired absorption of lipids through the intestine;
- congenital anomalies hemostatic systems (Von Willebrandt's disease, hemophilia A and B);
- disruptions in the mechanism for transporting bile to the duodenum;
- various liver pathologies (hepatitis, cirrhosis);
- hemorrhagic disease of newborns caused by insufficient production of vitamin K by the liver.
Consequences of high blood clotting - the formation of blood clots
Also, sometimes there is an increase in INR in a blood test when taking drugs of certain groups, such as antibiotics (Blemaren, Diclofenac), anabolic steroid and hormones thyroid gland of synthetic origin. If the described parameter reaches a value of 6 units or higher, this means that treatment must be started as quickly as possible.
Otherwise, any, even minor, injury will be enough to develop heavy bleeding which will be very difficult to stop. Such indicators are dangerous for patients suffering from ulcerative and inflammatory diseases gastrointestinal tract, vascular diseases of the brain, hypertension and renal pathologies. They need to be aware that the higher the INR, the greater the risk of bleeding.
Low values
If the decrypted analysis showed a decrease in the parameter, then the reasons for this may be the following:
- tendency to thrombosis, blood thickening;
- the serum was for a long time in a refrigerator;
- biomaterial was taken from central vein using a catheter;
- tall or low values hematocrit (its norm is 0.4-0.5 units);
- increased concentration of antithrombin III in the blood sample;
- taking anticonvulsants, diuretics, glucocorticoids or contraceptives.
A reduced INR is a clear indication for the appointment of repeated and additional diagnostic methods. It should be noted that in such cases, a consultation or consultation with a highly qualified specialist is often required.
Such a change most likely requires therapy and is dangerous to human health. Therefore, regular monitoring of coagulation parameters is an important examination that should not be neglected.
General recommendations. Indicators characterizing the quality of functioning of the hemostatic system enable the doctor to assess the risks of life-threatening bleeding or the development of blood clots. Therefore, if at some stage of the examination or before surgical intervention If any of them is prescribed, such diagnostics should not be neglected. These are quick and simple tests, and also relatively affordable, but even if it is expensive, it will be much more expensive to treat the disease.
INR is elevated - what does this mean? Each person who, based on the results of the diagnosis, has been prescribed blood-thinning drugs by a doctor must constantly monitor the ability of the blood to clot. An increase in INR or a decrease in the level of this indicator - important factor, allowing you to monitor the effectiveness of medication. Monitoring this parameter allows you to evaluate the effectiveness of treatment and, if necessary, adjust the dosage and composition of medications taken. What does this indicator represent, and if the INR is elevated, what does it mean?
The concept of INR
Usually, in the results of a blood test, the value of the INR factor is not directly deciphered; a specialist from a medical institution interprets the results. However, the patient should have an idea of what this parameter means for the purpose of general awareness and monitoring of their own health.
So, INR is an abbreviation behind which lies the phrase “International Normalized Ratio”. It should be remembered that this is not a specific value of some blood indicator obtained during the study; the normalized ratio figure is calculated comprehensively, in several stages.
To set the value, the following information is used:
- information about the value of prothrombin time, which, in turn, is obtained by analyzing a blood sample for coagulation (the so-called coagulogram);
- normal average given time (usually it ranges from 11 to 16 seconds);
- international sensitivity index (abbreviated as MISI) of the substance thromboplastin. The latter is a special reagent used in blood tests. This substance is produced by various companies, and each batch has an accompanying data sheet indicating the sensitivity and purity of the MIC.
The INR figure is obtained by dividing the prothrombin time obtained during the study by the average value and raising the found quotient to a power equal to the MIC of the reagent used in diagnosis.
INR test
Analysis for the normalized ratio has a number of important features:
- The resulting figures refer to important meanings to assess the correctness and effectiveness of the use of blood thinning medications, especially anticoagulants indirect type(Warfarin, Sinkumar, etc.). The specificity of the work of these medications is to influence only individual coagulation factors. And only an INR study can give accurate indicators of the state of these specific elements of the coagulation system.
- The result obtained depends on how pure and sensitive the thromboplastin is used.
- Diagnostics can show the effectiveness of indirect coagulants.
Thus, the INR analysis allows doctors to find out the exact indicators of plasma coagulation. This method makes it possible to almost completely eliminate the occurrence of errors and the impact on the result of any internal or external factors. The analysis technique is standardized, and its indicators will be equally accurate in any laboratory. Thanks to these properties, an INR test allows specialists to correctly select the dose of an anticoagulant drug and “keep their finger on the pulse”, monitoring the progress of treatment.
This testing is performed only on patients who are taking a course of indirect anticoagulants. To monitor the effectiveness of the drug over time, tests are taken once every two to three weeks, although, as prescribed by the doctor, this can be done more often. In each specific case, the frequency is selected based on the existing pathology, the patient’s condition and the duration of treatment.
If the result of the INR study is stable, then the period is increased to once a month. Blood is taken for analysis on an empty stomach, taking a sample from a peripheral vein.
INR norms
The general rule applicable in this study, is that the plasma viscosity is inversely dependent on the value of the normalized ratio: the higher it is, the lower the viscosity. Normally, the INR value is around one, and a deviation may indicate the presence of pathologies, incorrect dosage or incorrect prescription of drugs.
Changes can be either larger or smaller:
- An increase in INR indicates an overdose of anticoagulants. This result should signal the doctor about the need to reduce the dose of medication, since the patient may develop complications in the form of bleeding.
- A decrease indicates the low effectiveness of drug treatment; the blood does not thin. This can lead to blockage of blood vessels with blood clots. To avoid this outcome, the dose of medication must be increased.
For adults healthy people the INR test shows normal values ranging from 0.7 to 1.3, and this norm is the same for both sexes. The only exception is during pregnancy, since a woman’s body undergoes significant physiological and hormonal changes, and coagulation should be monitored especially carefully. Women carrying a child are prescribed this test three times throughout the entire pregnancy - once per trimester.
INR in pregnant women may be slightly elevated, which is not a pathology in itself. However, an excessive increase in the indicator can be fraught with miscarriage or premature birth.
If the doctor suspects a similar outcome, he will order a repeat study, after which adequate therapy will be prescribed.
What does an increase in INR mean?
Among doctors, it is generally accepted that deviation towards an increase is extremely undesirable and even very dangerous. Excessive blood thinning will inevitably lead to a deterioration in its coagulability, significantly increasing the chances of bleeding, both external and internal. internal organs. If the INR is significantly greater than one, the attending physician is obliged to reduce the dose of anticoagulants taken by the patient.
In cases where high values are observed in people who do not take such medications, this may indicate:
- liver diseases;
- cancerous tumors;
- development of myocardial infarction;
- hemorrhagic disease;
- polycythemia;
- the presence of pre-infarction conditions;
- about problems with the outflow of bile.
If the INR factor exceeds 6 units, the person must be immediately admitted to hospital, since the risk of bleeding is extremely high, and treatment must be started as soon as possible.
When testing blood for INR norm confirms normal blood clotting. A significant deviation in this indicator can reveal disturbances in the functioning of the body and indicate serious diseases. What is INR? INR testing is recognized by leading experts as the most accurate and reliable method for studying the blood coagulation system.
In what cases is an INR test prescribed?
A biochemical blood test is the beginning of diagnosis and an integral part of medical examinations and examinations. Many patients are interested in INR, what it is, and how much it should be in the test results in adults. The study determines the blood clotting index. The normal INR level in a healthy person is in the range of 0.7-1.3; ideally, its result should be as close as possible to one. When taking anticoagulants, a clotting test helps determine whether the dose needs to be reduced or increased medicines.
The INR blood test is prescribed by the attending physician during the period of medical examinations, which is carried out annually during biochemistry. In the presence of certain diseases, the formation of prothrombin may be difficult or exceeded; in such cases, studies are prescribed more often. Analyzes are carried out when registering pregnant women, in preparation for surgical intervention And How general research patient's condition.
Prothrombin level indicator
The ability of blood to maintain a liquid state for normal circulation through the circulatory system and to clot during damage and injury is provided by a complex protein - prothrombin. Its indicator as a result of the analysis allows you to determine the tendency to form blood clots or bleeding.
Prothrombin is formed in the liver with the help of vitamin K.
This protein performs important function, and to determine its level there are several methods:
- The Quick method determines protein activity in percentage terms.
- Prothrombin index (PTI) is the ratio of the prothrombin time of a healthy person to that of a patient.
- International normalized ratio (INR) is the ratio of a patient's prothrombin time to the prothrombin level of a healthy person.
- Prothrombin time (PTT) displays the clotting time of blood plasma in seconds.
As an international normalized indicator in modern medicine IPT or INR is used. At normal conditions for a blood sample, the coagulation rate is close to unity. The INR blood test is approved by the World Health Organization and provides diagnosis and monitoring of changes in the health status of patients.
Analysis results
Any laboratory tests must be interpreted by a qualified specialist. Index Blood INR determines the ability of blood to clot at a certain speed. For men and women taking various medications, normal levels may differ from standard values.
The INR level in the blood of women during pregnancy can change according to changes in hormonal levels, including age. The table of norms for healthy people is as follows:
After 50-60 years, the norm may change slightly. For children in the first year of life, normal values are within 1.
In practice, a blood test for INR close to one (0.8-1.25) is the norm. A decrease or increase in the indicator relative to the presented standards is extremely undesirable and indicates a risk to the patient’s health. The INR test result and interpretation can be understood by every patient. The final conclusion can only be made by the attending physician, taking into account all factors, which means that only a specialist should decipher the analysis.
Low level of clotting
If the INR is low, what does it mean? Reduced rate blood clotting causes the risk of blood clots and cutting off blood supply to vital organs. Therefore, your doctor may prescribe a blood thinner. drug treatment(anticoagulants) and additional laboratory tests. Many diseases and medications can reduce the level of the indicator. INR is below normal for the following diseases:
- By-effect anticonvulsants, diuretics, hormones (including contraceptives)
- Thromboembolism during pregnancy and after childbirth
- Vitamin K deficiency
- Physical trauma (including tissue necrosis)
- Congenital deficiency of clotting protein
In some cases, due to technical errors in blood sampling, the INR is reduced. Also, a low clotting rate will occur if the sample has been stored in the laboratory for too long. Only if the standards are strictly followed will the test result be correct.
High level of clotting
An increase in INR for a person who is not taking medications that affect blood clotting indicates hypocoagulation. Low blood clotting causes the risk of heavy bleeding and large blood loss even with minor physical injuries. An increase in INR can be facilitated by taking various medications. Based on the research results, the doctor carries out treatment, gradually reducing the dose of medication. If the INR test is above 6.0, the patient is subject to immediate emergency hospitalization and a drug that lowers the coagulation rate is prescribed. The INR may be elevated in patients not taking anticoagulants for the following reasons:
- A heart attack or pre-heart attack and other heart diseases can increase the rate.
- Pathological liver damage (cirrhosis, obstruction of bile outflow, etc.)
- Malignant neoplasms
- Increased number of red blood cells in the blood (polycythemia)
- Coagulopathy in infants caused by vitamin K deficiency
- Gastrointestinal diseases
- Side effect antibacterial agents, antibiotics or hormones
It is especially important to control levels after 50 years. Doctors recommend getting tested every year from the age of 50.
How to get tested
Patients undergoing inpatient treatment and taking anticoagulants are tested daily. When the condition stabilizes, the frequency of tests is reduced to once a week. After discharge from the hospital, on the recommendation of a doctor, the INR is checked once every 2-3 weeks. To do this, the patient visits the laboratory or uses a special portable device independently. Depending on the type of medication (direct or indirect) and the doctor's orders, blood clotting levels may be measured once a month or less often.
The attending physician is responsible for the referral for analysis and its subsequent interpretation. Blood donation is carried out in a special medical institution or laboratory. In some cases, the therapist can conduct the analysis himself. In laboratory conditions, venous blood is used. Before submitting the sample, you must adhere to general rules preparation for analysis.
Blood is donated on an empty stomach; alcohol, fried and smoked foods are excluded 2 days before blood collection.
Patients can conduct research themselves using a special device. A portable device for testing INR is available for purchase in pharmacies and online stores. The device is equipped with a display on which the result is displayed. To carry out the test skin covering The finger is pricked with a disposable sterile scarifier and the required amount of blood is applied to the test strip. The sample is placed in a portable device and after a short time the test result appears on the screen.
A laboratory blood test for INR according to the standard approved by WHO is an international indicator that is understandable to a doctor in any country in the world. This analysis can be used to diagnose many serious illnesses. When taking drugs that reduce the activity of blood coagulation, an INR test is carried out frequently and helps to monitor the effectiveness of treatment and adjust the dosage of drugs.
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In this article we will look at the decoding of INR in a blood test.
The INR can tell little to a person who is not medical worker. To understand what these letters mean, we will next familiarize ourselves with the features of the blood coagulation system. In addition, we will find out why the test analysis is prescribed, what its normal values are, to whom it is recommended, and in addition, we will find out how often it should be carried out. So, what is the INR norm and what control methods are usually used?
The interpretation of INR in a blood test should only be carried out by a qualified specialist.
What is INR?
Long-term use of anticoagulants should be accompanied by control of blood clotting. It can be performed in a laboratory by donating blood for analysis.
The INR in the blood is also deciphered there.
INR (we are talking about the international normalized ratio) is important laboratory test, reflecting the ratio of the patient’s thrombosed time to the value of this criterion in a healthy person. Such standardization of prothrombin indicators allows doctors to carry out various ways studies of the state of the blood coagulation system to a single, as well as generally accepted value. This laboratory test gives stable results that are the same when performing the test in different laboratories. The INR test is approved by various international companies and experts from healthcare organizations.
Why is it necessary?
The introduction of INR standards allows for effective control over the quality and safety of therapy for patients who are prescribed drugs to thin the blood (for example, Warfarin along with Syncumar and Finilin). Anticoagulants are prescribed if there is a tendency to increased formation of blood clots, which is observed in many pathologies, for example, with thromboembolic complications, in the presence of coronary insufficiency, myocardial infarction, heart defects, pulmonary embolism, thrombosis, thrombophlebitis, etc.
What does the increase indicate?
An increase in the INR indicates a predisposition to bleeding, and the doctor decides to reduce the dosage of anticoagulants. When the values of this test decrease, the patient's risk of developing blood clots increases. Such indicators indicate the low effectiveness of blood thinning drugs, and the doctor decides to increase the dosage.
When decoding INR in a blood test in adults, they rely on certain standards.
INR norm
In healthy people normal indicators INR studies (in both women and men) range from 0.6 to 1.4. As a rule, the following values are recorded: from 0.84 to 1.23, that is, closer to unity. When using Warfarin and other anticoagulants, normal values for this test should be from 2 to 3 units. It is this value that ensures reliable prevention of thrombosis. Now let's move on to decoding INR and PTI in a blood test.
PTI is the prothrombin index.
Analysis transcript: increase
Changes in INR values in people who did not take blood thinning medications indicate all sorts of things going on. pathological disorders in organism. An increase in the INR value greater than one indicates possible development such pathologies:
- Availability congenital pathologies coagulation system.
- Vitamin K deficiency human body.
- The appearance of liver pathologies.
- Impaired absorption of fats in the intestinal area.
- A side effect of anti-gout drugs, and also some antibiotics, anabolic steroids and steroids.
First of all, such hypocoagulation is extremely dangerous due to the occurrence of internal and external bleeding. INR indicators are critical when deciphering a blood test of more than 6 units. Such surges are especially dangerous in the presence of hypertension, inflammatory or ulcerative lesions digestive system. It is also dangerous for pathologies of the vascular and urinary systems. In such situations, the patient is prescribed urgent hospitalization and compulsory treatment.
Interpretation of INR analysis: decrease
A decrease in values below one indicates the possible presence of the following pathologies or laboratory errors:
- The presence of an increase or decrease in hematocrit.
- Increased amount of antithrombin III.
- Adverse reactions against the background of the use of contraceptives, glucocorticoids, anticonvulsants or diuretics.
- In the event that blood was drawn for research from a catheter located in the central vein.
A change in the INR in patients who took Warfarin or any other anticoagulants indicates the need for dosage adjustment of these drugs. Hypocoagulation (decreased blood clotting and increased INR) can lead to bleeding, and in such cases the dosage of drugs is reduced.
External bleeding in such cases can be provoked by even minimal mechanical stress or trauma. As for internal bleeding, they are caused (cavitary, uterine, gastric and others) by any disease and physiological process (for example, menstruation). If a patient has hypercoagulability, the risk of blood clots increases and it is likely that severe complication(for example, thrombosis). In such cases, the dosage of anticoagulants is increased.
We continue to consider the interpretation of INR in a blood test in adults and the norm.
Assignment for a study on INR and normal indicators
A blood test for INR is prescribed according to certain indications. The normal values for this test may vary depending on the patient's underlying disease. Indications are usually as follows:
- Conducting preoperative examination of patients. The norm in this case is usually closer to unity (from 0.8 to 1.2, as a rule, from 0.83 to 1.24).
- Use of drugs to thin the blood (for example, Warfarin). The norm is from 2 to 3 units.
- In the treatment of pulmonary embolism. The norm is from 2 to 3 units.
- Conditions after prosthetics aortic valve. The norm is from 2 to 3 units.
- Condition after prosthetics mitral valve. The norm is from 2.4 to 3.4 units.
- Preventative treatment in the presence of heart defects. The norm is from 2 to 3 units.
- Treatment of deep vein thrombosis immediately after surgical operations. From 2 to 3 units is the norm in decoding.
Women and men who take blood thinning medications are given at certain time intervals, which are determined individually by the doctor. At the beginning of the disease, when the patient is in the hospital, such tests are performed daily. Patients are then advised to monitor their INR once a week, and if the test is stable, the frequency of tests can be reduced to once every three weeks.
It is important to remember that the INR norm in a blood test for men when deciphered is the same as for women.
In what cases are patients prescribed an extraordinary INR test?
The following changes in the patient’s life or symptoms of hypocoagulation may be the reason for prescribing extraordinary tests:
- The presence of long-term colds or other diseases.
- Changes in concomitant therapy regimen.
- Changes in lifestyle or diet.
- Abrupt climate change.
- The appearance of unmotivated nosebleeds.
- The appearance of bleeding gums along with the causeless formation of hematomas.
- The appearance of blood in the urine.
- The presence of long and heavy menstruation among women.
- The appearance of streaks of blood in the sputum, and also in the vomit.
- The appearance of blood in the stool.
- Against the background of prolonged bleeding from cuts.
- For unexplained joint pain, pain, and swelling while taking blood thinners.
Independent deciphering of INR and PTI norms in a blood test is strictly not recommended.
Features of medical research
You cannot donate blood for this test after physiotherapeutic procedures, intense physical activity, massage, injections or intravenous infusion. All this can distort the obtained result. When using anticoagulants immediately before submitting biomaterial for INR determination, the entire daily dosage of the drug should be taken at approximately five o'clock in the evening the day before the analysis.
For research purposes, biomaterial is taken from a peripheral vein, as during a regular analysis. Blood is given for INR testing on an empty stomach, no less than eight hours after eating. True, you shouldn’t fast for more than fourteen hours before undergoing the study.
In a test tube, the blood is mixed with a preservative, the plasma is separated from the cell sediment, and pure serum is used for subsequent research. Citrate binds calcium ions and prevents blood from clotting. In the laboratory, calcium is added to the plasma to neutralize preservatives. In addition, thromboplastin is added and the time required for pure plasma to clot is assessed. This is the prothrombin time. After all the tests have been completed, the INR is calculated.
Determination of the prothrombin time period according to Quick
It is worth noting that some laboratories use more modern methods for assessing coagulation, namely, we are talking about determining the prothrombin period. In this case, several dilutions of plasma are carried out. The procedure takes one business day. If the result is urgently needed, some laboratories can provide it within two hours, but for an additional fee. When treated with indirect coagulants, the patient needs to have an INR test for coagulation once every three weeks. After this, the doctor will select the dose of drugs for the patient, and then the study can be carried out much less frequently, approximately once every eight weeks.
Where can I decipher the INR norm in a blood test?
Where can I donate blood for INR?
You can carry out such a test in the following ways:
It is most convenient to do this test at home, since the patient does not have to visit the clinic very often, donating venous blood and wasting his time waiting in queues. To perform this test, you need fresh blood from your finger. A completely painless puncture is performed using a special device, which is a scarifier. Test strips are inserted into a measuring device equipped with a display, onto which a blood sample is applied. After a short period of time, the INR value is displayed on the display. Using such a portable device is easy, convenient and simple.
An INR test, according to WHO recommendations, is prescribed for all methods of therapy that require constant monitoring of blood clotting. It shows the condition most accurately circulatory system person. This study was approved by all leading experts in anticoagulant therapy monitoring and antithrombotic treatment.
We looked at the interpretation and norm of INR in a blood test.
Blood test for INR and PTI (prothrombin index) - what is it? The study allows us to obtain data on its coagulation properties, that is, its ability to clot. Its increase, as well as its decrease, can lead to severe consequences. These tests are very important in clinical practice for diagnosing various diseases, for monitoring ongoing treatment with anticoagulants.
What are INR and PTI?
Elderly people and those suffering from cardiovascular diseases have not only heard about INR and PTI blood tests, but also have them taken more than once as prescribed by a doctor. Why do doctors pay so much attention to these tests and oblige their patients to take them regularly?
The fact is that both tests are indicators of the state of the blood, or more precisely, its viscosity and ability to clot. More liquid blood circulates well through the vessels, thicker ones impede blood circulation and promote the formation of blood clots.
The doctor observing the patient must have information about the state of his blood in order to choose the right treatment. This applies mainly to diseases of cardio-vascular system, vascular atherosclerosis, which are the main “killers” on the planet today.
The abbreviation INR stands for International Normalized Ratio., that is, uniform international standards blood tests and parameters. Regardless of the country in which the patient is located, the same criteria will be followed when providing assistance to him.
The PTI analysis is the prothrombin index, which reflects the patient’s blood coagulation as a percentage of the control blood sample, which is taken as 100%. This is a simpler test than the INR and can be variable depending on the type of laboratory reagents.
Determination of the prothrombin index is necessary for calculating the INR; there is an inversely proportional relationship between them: the higher the PTI, the lower the INR value and vice versa.
Why measure INR and PTI?
IN medical practice INR analysis is very important for monitoring blood clotting ability in patients taking tableted (indirect) anticoagulants, for example, warfarin, phenylin, tromexane and others. They are often prescribed for conditions where there is a threat of thrombosis: disorders heart rate, blood thickening, severe vascular atherosclerosis, thrombophlebitis, increased prothrombin.
Treatment with anticoagulants should always be carried out under the control of coagulation, because an insufficient dose can only “spur” thrombus formation, and an excessive dose, on the contrary, can reduce clotting and lead to the development of bleeding.
It is the INR analysis that reflects the most objective picture of blood clotting, regardless of the time of day, food or liquid intake.
An analysis of the prothrombin index (PTI) reveals the very fact of a decrease or increase in blood clotting. It is always prescribed before operations, childbirth, blood transfusions and other procedures, and is prescribed to patients with cardiovascular pathology and the elderly. Deviation of PTI from the norm is an indication for examining the patient to determine the cause of the violations.
Technique and frequency of blood sampling
Blood for INR analysis is prescribed by the doctor conducting anticoagulant treatment, usually 2 times a month, more often if necessary. If treatment is adjusted and the patient’s condition is stable, INR monitoring is carried out once a month.
The test is taken in the morning on an empty stomach, you should not drink alcohol the day before, you need to limit physical exercise . Blood for analysis is taken from a vein in the laboratory as prescribed by a doctor in the usual way, as for other studies.
Today, the problem of determining INR has been greatly simplified; it can be monitored even at home by purchasing a portable analyzer (CoaguChek XS). It allows you to receive information about your blood condition much more often without visiting a clinic or puncturing veins. All you need is a small drop of capillary blood from your finger, and the analysis itself is carried out by testing on paper strips, which are stored for up to 1.5 years.
The device performs electrochemical analysis, is quite accurate and complies with WHO international recommendations.
An analysis for PTI is also taken on an empty stomach in the laboratory, subject to the same rules. Blood is taken from a vein or from a finger (capillary), and its indicators will be slightly different.
Decoding the result
When deciphering the results of a blood test for INR, its age norms are taken into account, which are presented in the table.
INR norms
The INR level in the blood does not differ between women and men. INR values can deviate from the norm in one or the other direction.
Increasing INR
An increase in the test value indicates a decrease in blood clotting, the reasons may be the following:
- Long-term or excessive use of tableted anticoagulants.
- Prothrombin protein deficiency.
- Vitamin K deficiency.
- Liver diseases.
- Kidney diseases.
- Blood diseases (leukemia, erythropathies).
- Polycythemia.
- Long-term use of hormonal drugs.
An increase in the INR indicates the likelihood of developing hemorrhagic syndrome(bleeding), and requires the appointment of hemostatics: vitamin K, dicinone and other drugs.
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Decrease in INR
A decrease in the indicator is evidence of hypercoagulation in the blood, that is, an increase in its coagulability. This may be in the following cases:
- In case of circulatory failure.
- For liver failure.
- In patients with hypothyroidism, myxedema.
- For obesity.
- During acute inflammatory diseases with an increase in body temperature.
- After drinking alcohol.
A decrease in the indicator, on the contrary, indicates blood hypercoagulation and the risk of developing thrombosis. In these cases, anticoagulants are prescribed with regular monitoring of blood clotting tests.
PTI standards
When assessing a blood test for the prothrombin index (PTI), the patient’s age is also taken into account; normal age indicators are presented in the table (the norm for women and men does not differ):
The analysis takes into account the increase or decrease in the prothrombin index.
PTI deviations
An increase in PTI levels should alert you: this indicates the likelihood of blood clots forming in the patient, which means that a heart attack or stroke may develop. An increase is also typical for oncological diseases, polycythemia (red blood cell disease), with bleeding.
A decrease in the prothrombin index may be the result of a lack of vitamin K, the prothrombin protein, which occurs in diseases of the liver, where it is synthesized. There may also be an inherited deficiency of clotting factors.
Indications for analysis of INR and PTI
The purpose of the INR analysis is actually to determine the time of formation of a blood clot, which reflects the coagulating properties of blood in this moment. In medical practice, it is used to monitor treatment with indirect (tablet) anticoagulants, most often warfarin. This is necessary to maintain normal level blood clotting in various diseases (cardiovascular, oncological, endocrine and others).
A test for PTI is prescribed in the following cases:
- When passing full examination patient;
- In the presence of vascular pathology (atherosclerosis, heart attack, stroke, arteritis, thrombophlebitis, varicose veins veins);
- For thrombosis and thromboembolism;
- For liver diseases with impaired liver function;
- Before invasive medical manipulations: blood transfusion, surgery, organ transplantation;
- Before childbirth;
- For bleeding;
- At DIC syndrome(severe pathology - disseminated intravascular coagulation).
Both analyzes are also carried out at regular examination patients of the dispensary group with various diseases, in which a violation of the coagulation system is possible.
In the article, we looked at what an analysis for INR and prothrombin index (PTI) is, as well as how much it should be normal.
