What is a prothrombin test? Based on the mechanism of action, they are divided into

A blood test for the prothrombin index (abbreviated as PTI) is very important indicator necessary for the initial diagnosis of bleeding disorders. It makes it possible to timely determine the patient’s predisposition to thrombosis and hemorrhage of different nature origin.

Any coagulation disorders (from the Latin coagulatio - thickening, coagulation) inevitably lead to the emergence and development of very life-threatening diseases. To determine the cause of the disease, confirm or exclude the diagnosis, the patient is prescribed a blood test for PTI. Norm of prothrombin index healthy person is its fairly stable indicator.

General information about prothrombin

Prothrombin called a special protein that is responsible for blood clotting. This substance, when damaged and wounded during the coagulation chain, is transformed into the most important component of this system - serine protease (thrombin). The wound becomes clogged with the resulting blood clot, which prevents large blood loss in humans.

A blood test, during which the prothrombin index is detected, determines the ratio of the blood clotting time of the patient and a healthy person. Based on the level of this index, experts estimate the concentration of prothrombin in the blood plasma. The analysis results are displayed as percentages.

Deviations of PTI from the norm in blood tests

With an increase in the prothrombin index, the risk of blood clots in blood vessels, veins and arteries increases, and with its deficiency, significant hemorrhages can occur.

Every person, especially after the age of forty, is obliged to be interested in the question of whether the blood test for PTI corresponds to the norm. This helps to detect damage in a timely manner and prevent the progression of deadly diseases. Lesions are the cause of thrombosis, strokes, heart attacks and other extremely serious diseases.

Deviations of the PTI indicator from the norm are most often associated with liver pathologies, since this is where the synthesis of this protein occurs. From which we can conclude that the analysis makes it possible not only to recognize blood disease, but also to diagnose liver disease. Before surgical intervention Patients are required to undergo a blood test for PTI.

Normal values

Specialists involved in decoding blood tests consider the norm for PTI in an adult to be from 78 to 142%. However, during therapy with some drugs, noticeable deviations may occur, but in such cases they can be considered normal.

The PTI rate in the blood test of women during pregnancy may also change, which will also not be a sign of the disease, but correction will be necessary.

Today, qualified doctors use the PTI table according to Quick to more accurately determine the blood clotting index. This graph is based on prothrombin activity in the blood of healthy people tested at different medical institutions, so it is considered a very reliable source.

In conclusion, it should be noted that the PTI norm in a blood test is approximately the same in men and women.

Why might the index be downgraded?

The coagulability index directly depends on the activity of prothrombin in the blood. If, when deciphering a biochemical blood test, the PTI norm is not maintained, and, say, its level is reduced, then there is a threat of severe hemorrhages. In particular, bleeding in the brain and abdominal cavity. A reduced prothrombin index is observed due to the following reasons:

Elevated prothrombin levels

Deviation from the norm of PTI in biochemical analysis blood in the upward direction indicates that the blood is clotting too quickly, which can lead to the formation of blood clots, which can disrupt blood flow and lead to serious consequences. An increase in PTI is observed due to the following reasons:

genetic factor in pathogenesis;
increased concentration of red blood cells;
malignant tumors and neoplasms;
heparin deficiency;
third trimester of pregnancy;
use of certain medications containing hormones.

Decoding the results

Today, there are several methods for determining deviations or norms of PTI when deciphering a blood test. For this reason, there is a risk of setting misdiagnosis, since indicators may vary depending on the laboratory.

An analysis to determine the activity of prothrombins in the blood must be deciphered by the attending physician, since only he can fully take into account everything possible factors, affecting the index.

Abroad, the PTI blood test has not been carried out for quite a long time; in countries with developed civilization, the international normalized ratio (INR) is used - a study of blood clotting. The data from this analysis is more accurate and has more standard forms of calculation. In this regard, in modern Russian clinics, instead of IPT, an INR study is carried out.

Be that as it may, determining the deviation of the prothrombin level from the norm using a PTI or INR blood test and making the correct diagnosis is the task of the attending physician.

Distinctive features of female analysis

Experts pay attention special attention on the concentration of prothrombin in the blood of pregnant women. A study on the prothrombin index should be carried out for every pregnant woman, since this way doctors will be able to timely detect any possible deviations. If suddenly expectant mother If deviations of the PTI indicator from the norm are detected in the blood test, the doctor will prescribe corrective drug therapy for her.

But, unfortunately, many pregnant women do not take into account the doctor’s order to undergo an IPT test. They believe that this indicator is completely unimportant for health, since they feel great. But as a rule, statistics most often show the opposite. According to its results, about 10% of pregnant women who did not test for prothrombin activity in the blood, unfortunately, died during childbirth from sudden onset of severe hemorrhages or due to a blood clot.

In what cases is it necessary to take the test regularly?

A blood test for the prothrombin index is most often prescribed before surgery and during pregnancy. But there are patients who need to be tested regularly in order to monitor the effectiveness of therapy. These include:

People with diseases of the cardiovascular system.
Patients with a cardiac implant.
Patients who have been diagnosed with atherosclerosis.
People who suffer from varicose veins.

The prothrombin index must be monitored for women and men over 50 years of age, since they belong to a special risk group for the occurrence of cardiovascular diseases. Timely diagnosis of these diseases can save the life of an elderly person. Today in our country, about 70% of older people die from stroke and heart attack.

Also, PTI levels should be regularly checked in patients suffering from the following diseases:

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

In addition, the level of PTI must be monitored during the course of hormonal and heparin treatment. Drugs of these groups can have a strong effect on blood clotting. Uncontrolled data reception medicines may lead to life-threatening consequences. Do not forget that any medication must be taken strictly as prescribed by the attending physician, even if we are talking about traditional medicine.

Rules for taking a blood test for IPT

As with any blood test, the material for this study must be submitted to morning time days and on an empty stomach. During the week before blood sampling, you should exclude alcoholic beverages and fatty foods from your diet.

Immediately before the pick-up, you should not drink coffee or tea, and it is also strongly recommended not to smoke. You also need to be in a balanced state and not be nervous. The listed factors can influence the results of the analysis. The use of any medications, and even herbal teas, must be reported to your doctor.

If any deviations from the norm are detected, the specialist will prescribe additional research, which should help determine the cause of the blood clotting disorder.

It is worth remembering that deviations in the prothrombin index do not relate to independent diseases, this is just the body's reaction to pathogenic process. Determining the root cause of the deviation is very important for prescribing appropriate treatment. The results of the analysis should only be deciphered by the attending physician.

Prothrombin is found in blood plasma and has decisive influence in the process of blood clotting (another name is coagulation). Therefore, deviations of prothrombin from the norm cause increased bleeding or, conversely, indicate a risk of thrombosis. It is very important for doctors to know about this possibility if surgery is necessary, as well as when prescribing medications that affect blood clotting. Doctors also use this indicator to judge the state of liver function, gastrointestinal tract.

Prothrombin is a complex glycoprotein molecule. The decoding of this term is simple - glucose plus protein, in other words: a complex that combines carbohydrates and proteins. Prothrombin is a component that is activated on one of the initial stages after damage to body tissues that causes bleeding. The stages of blood clotting are as follows:

After vascular damage, platelets are activated and adhere to damaged tissues, stick to each other, forming a platelet plug.
At the same time, platelets begin to secrete substances that make the plug more dense.
At the same time, prothrombin is activated.
Thrombin is formed from prothrombin, which is synthesized under the action of a specific enzyme called prothrombinase.
Thrombin then produces fibrin from fibrinogen.
Fibrin, together with platelets contained in the blood, forms a blood clot.

Based on this, it is obvious that prothrombin deficiency increases bleeding time. The lack of this component is caused mainly by a deficiency of vitamin K, which plays important role in the process of prothrombin synthesis by liver cells. Vitamin K deficiency can be caused by various circumstances, and is often accompanied by impaired bile production, which signals problems in the liver. Among the main causes of vitamin K deficiency is impaired absorption or impaired synthesis by intestinal microflora.

It is worth noting that the lack of prothrombin can be explained by other reasons. For example, substances that prevent blood clotting, treatment with anticoagulants indirect action, insufficient supply of bile.

How the analysis is carried out

If we talk about such a thing as prothrombin time (PTT), then you should know that this is the name of a blood test that measures the time it takes for plasma (the liquid part of the blood) to coagulate, that is, to coagulate or thicken.

Prothrombin time is measured to measure the blood's ability to form clots. Knowledge about it has a direct bearing on the dosage of anticoagulants, the degree of liver damage and the amount of vitamin K in the body.

The essence of the analysis is as follows: if damaged blood vessel The body activates the blood clotting mechanism, which stops bleeding. The coagulation process involves special proteins called coagulation factors, whose task is to promote coagulation. The PTT test accurately measures the ability of these substances to affect blood clotting.

A PTT blood test is carried out like a regular blood test: the material is collected in a tube and analyzed. The technician then adds various chemicals to the blood sample. The time that passes from the start of adding reagents to the thickening of the blood is called prothrombin time.

The American biochemist Armand James Quick is related to the existence of this type of research. At the beginning of the last century, Quick studied the biochemistry of processes in the liver, in particular, what effect vitamin K and anticoagulants have on its work. As a result, he determined the norms of hemostasis (the process of stopping bleeding). In 1935, Quick published the prothrombin time (PTT) technique that later bore his name (the test is now known as the Quick test).

Features of the analysis

The interpretation of the prothrombin test largely depends on the laboratory in which the prothrombin test was performed. Prothrombin time is usually related to the international normalized ratio (INR), which is 0.8-1.2. INR is calculated as the ratio of direct proportionality of the prothrombin time obtained in the test to the normal prothrombin time in a healthy person (INR = PTT test / PTT norms).

For men and women, the prothrombin rate is the same and ranges from 12.7 to 15.4 seconds. In pregnant women, the PTV transcript shows a faster rate of blood clotting:

First trimester – 9.7-13.5 seconds.
Second trimester – 9.5-13.4 seconds.
Third trimester – 9.6-12.9 seconds.

The increase in clotting rate during pregnancy is explained by the fact that by this method the body reduces blood loss, which is always observed during childbirth. But on the other hand, this leads to the formation of blood clots in the veins of the legs and pelvis. Fortunately, statistics show that blood clots are rarely a concern during pregnancy: there are only 1-2 cases per 1000 women giving birth, which means there is no need to panic, unless, of course, the woman is at risk.

The formation of a blood clot in women during pregnancy is most likely in the following situations:

During the first trimester of pregnancy or first three months after childbirth.
If you have close relatives with thrombosis.
Mutations of the prothrombin gene.
The woman smokes or is constantly exposed to tobacco smoke.
Age over 35 years.
Overweight.
Frequent trips to other cities during pregnancy.
Expecting twins or triplets.
Sedentary lifestyle.
The previous birth was a cesarean section.

The appearance of blood clots in the veins during pregnancy is indicated by symptoms such as a feeling of swelling and distension in one or both legs, increased pain while walking. It may also be observed varicose veins veins in the legs (that is, they become enlarged).

The presence of such symptoms during pregnancy means that the woman must follow all the doctor’s instructions. Otherwise, complications are possible: blood thickening and a blood clot in the placenta, miscarriage, pulmonary embolism, heart attack.

Considering dire consequences, women are often interested in how to avoid blood clots during pregnancy. Doctors recommend paying special attention healthy image life, perform the physical activity and exercises recommended for pregnant women. It is also important to comply healthy diet, and of course, be regularly examined by a doctor.

Preparing for analysis

If your doctor has prescribed a Quick test, you need to properly prepare for the test. The time between the last meal and the procedure should be more than eight hours. Before donating blood for prothrombin, you must inform the doctor about all the products, medications, herbs, and supplements that the patient uses.

This is very important because many substances thin the blood and, in fact, increase prothrombin time. The doctor will tell you which foods you need to stop eating and how long it should take after that to donate blood from a vein and get correct results. You can only drink still water in the morning.

The day before the procedure, it is necessary to limit physical activity, since it greatly affects the composition of the blood. Before donating blood, you need to rest well and be less nervous. You must not smoke for an hour before donating blood.

As a rule, the results obtained as a result of a PTV test need to be understood relatively, since they largely depend on the laboratory where they are carried out, equipment, and personnel. The doctor conducting the decoding usually takes into account the error, since the indicators may deviate from the norm under the influence various factors even if the patient has properly prepared for the analysis.

If the result shows a deviation of the PTT from the norm, you should not be alarmed right away, since this does not always indicate a disease. Perhaps the patient made a mistake and ate food from the list of non-recommended foods. For example, the day before the analysis I drank a can of beer: from drinking any alcoholic drinks You must refuse three days before the test.

Therefore, if the results are negative, the doctor prescribes a repeat test. If in this case the transcript shows a deviation from the norm, he refers the patient for further examination to determine the reasons for too slow or rapid coagulation and prescribe the correct treatment.

One of important functions hemostasis in the body is to maintain the balance of the blood coagulation and anticoagulation systems. The main indicator of the state of the coagulation system is the prothrombin index, or PTI.

What is PTI and why is it needed?

The ability of blood to form a clot depends on the amount of prothrombin in the plasma. This protein is synthesized in liver cells, and for its complete synthesis it is necessary sufficient quantity vitamin K. The prothrombin test shows how ready the coagulation system is to form a blood clot.

Prothrombin index- This percentage clotting time of patient plasma and control plasma. This analysis is done in combination with other methods and allows you to assess the overall clotting ability of blood plasma.

A complete picture of the state of the coagulation system can be obtained based on coagulogram data, which includes:

blood clotting time;
prothrombin index;
prothrombin according to Quick;
fibrinogen level;
thrombin time;
prothrombin time;
antithrombin III level.

From correct ratio Blood clotting and anti-clotting factors determine how the body is adapted to sudden bleeding. At the moment of injury or internal rupture of a vessel, activation of the blood coagulation system begins. A whole cascade of events occurs in the body aimed at reducing blood loss and maintaining blood supply to the injured organ.

The end result of these reactions is spasm of the damaged vessel and the formation of a blood clot, which prevents further blood loss. After stopping the bleeding next task The body's adaptation mechanisms include restoring blood supply to the damaged area and eliminating the blood clot.

Both processes work parallel to each other, ensuring minimal tissue damage.

There are a number of diseases that lead to failures of this fine process regulation of hemostasis. In these diseases, the prothrombin index changes:

chronic liver diseases - hepatitis and cirrhosis. The change in hemostasis occurs due to a decrease in the formation of prothrombin in the liver tissue;
malignant tumors;
amyloidosis of various localizations;
other autoimmune diseases: rheumatoid arthritis, systemic lupus erythematosus;
severe pneumonia or kidney inflammation.

The prothrombin index also changes as a result of:

massive burns;
injuries with rupture of soft tissues and damage to internal organs;
myocardial infarction;
pregnancy complicated by late toxicosis and DIC syndrome;
septic blood poisoning;
volumetric surgical interventions;
long-term use hormonal contraceptives.

Since all these diseases and conditions occur with disruption of the hemostatic system, patients need to monitor coagulogram parameters, including the prothrombin index.

How to get tested

A coagulogram and prothrombin test are examined in patients:

Before surgical treatment and in the process of rehabilitation after surgery.
In pregnant women, as a screening diagnosis of hemostatic system disorders.
Those who have had a myocardial infarction.
To control the coagulation system after long-term use of hormones.
With heavy massive inflammatory processes, including sepsis.

Before taking the prothrombin index test, certain preparation is required. All foods with high content vitamin K:

All types of cabbage - broccoli, white cabbage, cauliflower;
All types of salads (plants) - lettuce, spinach, iceberg, arugula and others.

This limitation is due to the fact that the blood test for PTI depends on the amount of this vitamin. Therefore, so that the interpretation of the results is not distorted, before taking the test there, the patient is advised to abstain from these products for three days.

In addition to special dietary restrictions, before taking a blood test for IPT, it is necessary to limit the intake of medications:

Hormonal contraceptives;
Anticoagulants and acetylsalicylic acid.

This limitation is due to the fact that these groups of medications change the prothrombin index both up and down. The interpretation of results when taking these drugs will be distorted.

Interpretation of results

In a person without abnormalities in the hemostasis system, the prothrombin index ranges from 95-105%.

If the interpretation of the test result shows a result higher than normal, this means an increased readiness of the blood to form blood clots (hypercoagulation). Such conditions are fraught with the development of microthrombosis and circulatory disorders in organs. Hypercoagulation develops:

in a state of pre-infarction;
for malignant tumors.

Increased sensitivity of the blood to clot formation can lead to thromboembolism and shutdown of organs from the circulation.

If, when deciphering the results, the PTI turns out to be below normal, this condition is called hypocoagulation. In this case, the body is not ready for vascular damage.

The hypocoagulation state is especially important during pregnancy. If hemostasis is not corrected at the end of pregnancy, this can lead to massive bleeding during childbirth.

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What is it? Prothrombin is a protein involved in the blood clotting mechanism; its synthesis occurs in the liver with the participation of vitamin K. Clotting involves the transition of blood from a liquid to a thick state.

To function comfortably in the body, blood must have a liquid consistency. When blood vessels are damaged, a process of coagulation—thickening—must occur. The body cannot lose a large volume of blood and clog the vessels with numerous blood clots.

Laboratory analysis for prothrombin allows you to assess the quality of the coagulation mechanism.

Like any analysis, a prothrombin test is taken on an empty stomach. Patient who cannot perform this condition for health reasons, eats 4-5 hours before the procedure. Drugs that affect blood clotting cannot be taken before the test - the results will be far from the truth. If you refuse medicine If it doesn’t work, notify your doctor about taking it.

An analysis of the quality of blood clotting is necessary when the following diseases and suspicion of their presence:

Antiphospholipid syndrome in pregnant women (it is manifested by miscarriages, frozen pregnancies, placental insufficiency and other obstetric complications);
Liver pathologies;
Atherosclerosis, varicose veins;
Imbalance of vitamin K in the body;
Presence of autoimmune diseases;
Long-term use of indirect anticoagulants.

The prothrommin test may also be prescribed for other diseases to screen for coagulation. Under a microscope, the natural mechanism of blood clotting is recreated.

Potassium ions and thromboplastin are added to recalcified plasma. Prothrombin complex has several coagulation factors - analysis allows us to identify a deficiency or surplus of such factors.

Prothrombin time - what is it? (norm)

Prothrombin time is the period of blood clotting from the moment a mixture of potassium and thromboplastin is added to the plasma. Thromboplastin, used in laboratories, has a certain level of sensitivity to factors II, V, VII and X.

The normal prothrombin time is from 11 to 16 seconds, but the activity of the substance may vary depending on the sample. Accordingly, draw conclusions by comparing general meaning The result in seconds is incorrect. A relative assessment is required.

Prothrombin index - what is it? (norm)

The prothrombin index is the ratio of the fixed normal blood clotting time to the patient’s individual indicator. The prothrombin index can be determined more accurately using the INR (international normalized ratio) analysis.

The prothrombin index mathematically corrects the prothrombin time. The individual result in seconds is divided by the fixed norm of a healthy person and multiplied by the sensitivity coefficient of the taken thromboplastin. The number of the latter is from 1 to 3; it can be found in the universal international classification.

Remember, when determining the prothrombin index: the norm for women and men is the same - from 0.8 to 1.3. But the rate may vary depending on age and health status.

The results of the preoperative study should not go beyond 0.85 - 1.25. An indicator of 3.0 – 4.0 is observed in the patient, suffered a heart attack myocardium or suffering from serious cardiovascular diseases.

The normal prothrombin index is 2.0 – 3.0 in the case of:

Heart valve defects;
Chronic atrial fibrillation and taking Warfarin against its background;
Treatment venous thrombosis and prevention of deep vessel thrombosis after surgery;
Implantation of mitral and aortic valve prosthesis;
Treatment of thromboembolism in the pulmonary artery area.

A prothrombin index according to INR above 6.0 requires urgent hospitalization of the patient. This coefficient indicates high risk internal bleeding in various locations.

The situation becomes more complicated if the person has already had ulcerative lesions gastrointestinal tract, renal failure, hypertension and blood flow disorders in the brain. In this case, the potential risk of hemorrhagic (bleeding-related) infarctions in organs increases.

If unsatisfactory results of the analysis using the INR system are obtained, a repeat study is not required (the result is very sensitive and reliable). The index values do not differ depending on the type of laboratory material taken (capillary, venous blood).

The prothrombin index is calculated taking into account the sensitivity of thromboplastin to blood clotting factors.

Prothrombin according to Quick - what is it? (decreased, increased and normal)

For several decades now laboratory conditions prothrombin is calculated according to Quick. What is it? This is the percentage expression of prothrombin activity. The scientist proposed to compare the patient’s prothrombin time with the indicator of the dependence of this period of time on the number of prothrombin complex factors in the taken plasma. The result is a percentage.

The construction of the dependence allows you to very accurately estimate the coagulation index, but the sensitivity coefficient of thromboplastin is not taken into account.

This feature of the test affects the quality of the result in the area of critical values below and above the norm. In standard results and minor deviations from them, the INR and Quick index are directly proportional.

The test results card in any laboratory will contain prothrombin according to Quick. The norm is in the range of 78% - 142%. The indicator may be slightly higher than the average, but it should be within normal percentages.

IN healthy body Blood clotting is often increased - hypercoagulation is observed. This process is considered normal until a person develops any vascular diseases or chronic tissue damage. Their presence becomes a risk of blood clots.

Regular screening is necessary after blood thinning medications are prescribed. In some cases, a depot (the stage of accumulation of a substance) can form in the body from these drugs, which will lead to a state of hypocoagulation with increased bleeding.

In addition, the analysis results may also show the opposite process - hypercoagulation (increased coagulation activity). Indicators of insufficient blood density are observed much less frequently than excess blood density.

However, any pathology of prothrombin factors requires control or even treatment.

Increased prothrombin in men and women

Prothrombin in men and women over 45-50 years of age is often increased - more than 142% according to Quick. Hypercoagulation can be caused both by the presence of vascular diseases and by temporary factors. The latter include:

Imbalance of vitamin K, which interferes with the proper synthesis of prothrombin in the liver, where it is normally formed;
Chronic liver diseases and disorders of its functioning, which also interfere with the normal synthesis of prothrombin;
Congenital anomalies: deficiency of blood coagulation factors II, V, VII, X;
The presence of a heparin inhibitor in the coagulation mechanism;
Nephrotic syndrome, amyloidosis (deposition of a special pathological protein in organs);
Taking antiseptic, laxatives, anabolic drugs, hormonal drugs, nicotinic and acetylsalicylic acid, quinine, quinidine.

Increased prothrombin not due to the above factors indicates the presence of serious illnesses. So, diagnostic search is based on the following nosologies:

Thromboembolism (blockage of blood vessels with blood clots);
Polycythemia (increased number of red blood cells in the blood, including in connection with oncological processes);
Oncological diseases: leukemia, cancerous tumors various localizations;
Pre-infarction state of the body;
Myocardial infarction.

Prothrombin in women may be increased due to long-term use hormonal contraceptives, especially with an increased dosage of the estrogen component (from 30 to 50 mcg per tablet).

If the patient has serious vascular disease, birth control pills needs to be cancelled. Possible transition to hormonal drugs local impact(suppositories, vaginal ring).

Diet does not significantly affect blood clotting. You can reduce the Kwik score by several percent by adding daily menu"oxidizing" products. Improved results causes dietary deficiency fermented milk products, red and black berries, citrus fruits, fatty fish and the volume of water drunk.

Low prothrombin - what does it mean?

Low prothrombin is observed during hypocoagulation. This result indicates the body’s tendency to internal bleeding. A deficiency of coagulation factors occurs in the following situations:

Vitamin K deficiency is a violation of prothrombin synthesis;
Congenital deficiency of certain factors regulating processes in the blood;
Pathologies of the liver that interfere with the normal synthesis of coagulation factors;
Lack of fibrinogen in the blood (congenital and acquired);
Taking medications that reduce the blood's ability to clot.

A low prothrombin level indicates the following diseases:

Dysbacteriosis;
Pathologies of the gastrointestinal tract;
Prothrombin deficiency;
Hypovitaminosis.

Adjust slightly reduced rate prothrombin can be achieved with the help of foods containing vitamin K. Cabbage, carrots, bananas, apples, pears, spinach and lettuce will be useful.

The reason for poor results in diet concerns men more often than women. It is the male gender that prefers meat products vegetables. As a result of such addictions, a deficiency of vitamins appears in the body.

Prothrombin during pregnancy

For pregnant women, a test for prothrombin index is done in mandatory. During childbirth low rate may lead to heavy bleeding, and high - to premature contractions and even late miscarriage.

Therefore, it is very important to evaluate this indicator during gestation, especially if there are various complications both during this pregnancy and during the previous one.

During gestation, a blood test for the prothrombin index is taken at least 3 times (once per trimester). If the expectant mother is diagnosed with significant abnormalities, it is necessary to do a clotting test more often. The rate of prothrombin in the blood of women during pregnancy is lower than usual - from 70% to 120%.

Disturbances in the blood coagulation mechanism of pregnant women are indicated by:

Varicose veins on the limbs;
Bleeding and appearance noticeable bruises after minor damage;
Improper liver function;
A long period of lack of results when trying to conceive;
Conception through the IVF procedure;
Multiple pregnancy;
Fetal development lags behind norms;
Drinking alcohol, smoking by the expectant mother;
Long-term treatment with anticoagulants;
Multiple miscarriages.

Since prothrombin according to Quick decreases during pregnancy, the INR index also decreases. Changes are especially noticeable in the second trimester of gestation. Until the 13th week, the coefficient should correspond to the norm: from 0.8 to 1.3. Then the indicator decreases:

From the 14th to the 20th week, the prothrombin index according to INR ranges from 0.55 to 1.1;
From the 21st to the 28th week, the indicator can decrease to 0.5, but cannot exceed 1.15;
From the 29th to the 35th week the result is 0.6 – 1.17;
From the 36th to the 42nd week the index is from 0.55 to 1.15.

In the case of pregnant women, the INR indexing method is preferred. The indicators are quite low, and the Quick method produces errors at critical values.

> Blood test for prothrombin, INR (prothrombin time)

This information cannot be used for self-medication!
Consultation with a specialist is required!

What is the method used for, what does it define?

Prothrombin is one of the important factors blood coagulation systems. It is formed in the liver with the participation of vitamin K and circulates in the blood plasma. When interacting with thromboplastin and calcium ions, prothrombin is converted into thrombin, without which the formation of a blood clot is impossible.

Clinical diagnostic laboratories typically perform a prothrombin test, which is performed as the Quick prothrombin test, prothrombin time, international normalized ratio, or prothrombin index.

Prothrombin time (PTT) is the time period during which blood plasma clots when a thromboplastin-calcium mixture is added to it. Measured in seconds.

The international normalized ratio (INR) is the ratio of the patient's PT to the normal mean PT. The result of the analysis is the coefficient (decimal fraction).

Prothrombin index (PTI) is the percentage ratio of the clotting time of the control blood plasma to the clotting time of the plasma of the examined person. Expressed as a percentage.

The Quick determination of prothrombin differs from the previous test in that it uses several dilutions of control plasma. This allows you to get more exact result(also in percentage).

All these indicators are used to assess the state of the coagulation system and determine the effectiveness of anticoagulant therapy.

In what situations is research prescribed?

Changes in the listed indicators can occur either in the direction of increasing or decreasing their values. Clinically, this is manifested by signs of increased or decreased blood clotting.

The causes of increased clotting are big losses fluid without its timely replenishment (vomiting, burns), taking hormonal drugs, impaired permeability of vascular walls. Increased clotting observed in infections vascular pathology, pregnancy, DIC syndrome, after surgical interventions and is often manifested by various thrombotic complications.

With a decrease in blood clotting, the bleeding of wounds increases, bruises form in soft tissues With minor injuries, nosebleeds often occur. Poor clotting characteristic of hemophilia, liver diseases. It affects patients who take anticoagulants for a long time.

In all these cases, a prothrombin test is mandatory.

Which doctors prescribe the test, and where can it be done?

A referral for a study is issued by a therapist, surgeon, gynecologist, cardiologist, hematologist, oncologist, and less often by other specialists.

You can undergo examination in the laboratories of diagnostic departments medical institutions, conducting biochemical research blood.

What is the material for research and how to prepare for it

The material for the study is blood. It is taken from a vein immediately before analysis into a special tube with an anticoagulant.

Before the study, the doctor stops medications that change blood clotting. On the eve of the procedure, exclude fatty and spicy dishes, alcohol. It is advisable to avoid emotional and physical activity. Blood sampling is carried out on an empty stomach.

The test results are normal

Normal prothrombin time is from 11 to 16 seconds. The INR coefficient is 0.85–1.35. The prothrombin index is in the range of 80–100%. Prothrombin according to Quick – 78–142%.

Disadvantages of the method

The disadvantage of the method is the presence of many reasons that affect the accuracy of the study results (lack of clear standardization of the thromboplastin used, the influence of other coagulation factors).

Clinical significance research

The method helps to diagnose the pathology of the blood coagulation system, clarify the degree of its severity, and monitor the treatment. But prothrombins are only part of the body’s hemostasis system, and a prothrombin test cannot detect all disorders. Therefore, if indicated, it is necessary to carry out a comprehensive study of the blood coagulation system.