What tests are included in a blood coagulogram? Achtv in the blood: what is it, reasons for low and high, norms in the coagulogram. Indications for analysis

Extended coagulogram

Extended coagulogram– a set of studies of the blood coagulation system, which, in addition to the basic components (APTT, thrombin time, prothrombin time and prothrombin index, fibrinogen, antithrombin III), includes the determination of lupus anticoagulant, protein C, protein S, D-dimer and RFMC. Coagulological tests are performed in conjunction with a general analysis. The results of an extended coagulogram are used to diagnose and treat conditions accompanied by bleeding disorders, monitor anticoagulant therapy, determine the causes of miscarriage, and in preparation for operations and other invasive procedures. Blood is drawn from a vein; research methods are coagulometric. Each indicator has its own reference values. The time frame for completing a comprehensive analysis is from 1 to 2 days.

An extended coagulogram is a comprehensive blood test that is aimed at assessing various parts of hemostasis: coagulation, anticoagulation and fibrinolytic systems. The results are used to detect hyper- and hypocoagulation, that is, excessive or insufficient blood clotting.

Hemostasis is a set of blood factors that, on the one hand, maintain it in a liquid state, and on the other, promote clotting when blood vessels are damaged. Normally, the body maintains a balance between anticoagulant and coagulation factors. If it is disturbed, there is a tendency to thrombosis or bleeding. An extended coagulogram is used to identify the link whose activity is impaired and further correct the imbalance.

The first group of extended coagulogram tests is aimed at assessing the coagulation component of hemostasis. In the process of blood coagulation, there are external and internal pathways. The first is triggered by factor III - tissue thromboplastin, which is released from the walls of blood vessels and tissues when their integrity is violated. The internal pathway is activated by the interaction of blood components with the subendothelium of the damaged vessel; factors XII, XI, IX and VII are involved in it. After the formation of factor X, the coagulation pathway becomes common. In an extended coagulogram, tests for prothrombin (PTT, PTI, INR and Quick prothrombin), thrombin time, fibrinogen, and APTT are used to study the blood coagulation system. To evaluate anticoagulant mechanisms, a test is prescribed for antithrombin III, lupus anticoagulant, protein C, protein S. Plasma fibrinolytic activity is examined by tests for RFMC and D-dimer.

When performing an extended coagulogram, the research material is plasma isolated from venous blood. Analyzes are performed using various methods: photometric, colorimetric, immunological, using the orthophenanthroline test. Automatic and semi-automatic coagulometers are used. The extended coagulogram is widely used in hematology, obstetrics and gynecology, surgery, resuscitation, cardiology, phlebology and other areas of clinical practice.

Indications and contraindications

An extended coagulogram is used for a general assessment of hemostasis, diagnosis and monitoring of diseases accompanied by a violation of the external, internal and final pathways of blood coagulation, the activity of the anticoagulation and fibrinolytic systems. The study is indicated for DIC syndrome, venous thrombosis, thromboembolism, hemophilia, and antiphospholipid syndrome. The analysis is also carried out to assess the effectiveness of anticoagulant therapy and identify complications associated with it. The reason for prescribing an extended coagulogram may be frequent nosebleeds, bleeding gums, blood in the stool and urine, hemorrhages under the skin and joints, anemia, heavy menstruation, pain and heaviness in the legs, the appearance of vascular “networks” and “stars”. The reason for performing an extended study may be a deviation in the test results of the basic hemostasiogram.

In obstetrics and gynecology, an extended coagulogram is indicated for women who have a history of diseases with blood clotting disorders, recurrent miscarriage, as well as pregnancy complications: threatened miscarriage, placental abruption, fetal hypoxia. At the pregnancy planning stage, this study is used to diagnose the causes of infertility. In surgical practice, an extended coagulogram is carried out as part of the preoperative preparation of the patient and the identification of complications of the postoperative period. Screening of the blood coagulation system is indicated for hereditary predisposition to thrombosis and hemophilia.

Most extended coagulogram tests are not indicated for inflammatory diseases, including infectious and autoimmune diseases, since in these cases blood clotting temporarily changes and the indicators become uninformative. The study itself has no contraindications, but blood sampling is impossible if the patient is psychomotor agitated, has severe anemia or hypotension, or has frequent seizures. An extended coagulogram allows you to most fully assess the hemostatic system and accurately determine which links in it are disturbed. But for a correct diagnosis, the interpretation of the results should not be carried out in isolation, but in combination with the indicators of a general blood test with ESR and leukocyte formula, as well as with data from clinical and instrumental examinations.

Preparation for analysis and collection of material

Blood plasma is used to determine the parameters of the extended coagulogram. Its collection usually takes place from 8 to 11 am. The break between the procedure and the last meal should be at least 8-12 hours. Since stress, physical activity and smoking affect blood clotting, these factors should be eliminated at least half an hour before collection. If possible, all medications should be stopped in advance or the effect of taking them on test results should be discussed with your doctor.

Blood for research is taken from a vein. It is collected in a test tube with sodium citrate and mixed gently - this prevents the formation of clots. Over the next 2-6 hours, the material is delivered to the laboratory, centrifuged to obtain plasma, into which reagents specific for each test are then injected. Some of the samples are incubated and then applied to the substrate or combined with another reagent. The procedure and calculation of indicators are performed automatically in special analyzers - coagulometers. The duration of the study depends on the set of tests, most often it is 1-2 days, but can take up to 7-14 days (for example, when determining proteins C and S).

Normal values

In adult patients, the following values ​​of extended coagulogram tests are normally determined:

• Prothrombin test: prothrombin time (PTT) – 11-15 seconds; prothrombin index (PTI) – 95-105%; international normalized ratio (INR) – 0.8-1.2; prothrombin according to Quick – 78-142%;
• thrombin time – 16-21 seconds;
• fibrinogen – 2-4 g/l;
• APTT – 21-36.5 sec.;
• Anticoagulant system: antithrombin III – 66-124%; lupus anticoagulant – 0.8-1.2; protein C – 70-140%; protein S for women – 54.7–123.7%, for men – 74.1–146.1%;
• Plasma fibrinolytic activity: RFMC – 3.36-4.0 mg/100 ml; D-dimer – 0-0.55 µg FEU/ml.

However, the range of reference values ​​may differ between laboratories, since they use different reagents, analyzers, and sometimes research methods in general. Therefore, it is necessary to determine the norm using the form with the results (the “reference values” column). In addition, blood clotting changes during pregnancy and menopause, during periods of intensive growth and puberty, when smoking, and using certain medications. Temporary physiological deviations in coagulogram parameters are observed during physical activity and emotional stress.

Diagnostic value of the analysis

In diseases and conditions accompanied by increased blood clotting and the risk of thrombus formation, the parameters of the extended coagulogram change as follows: INR, PTT, fibrinogen and/or D-dimer exceed the norm, a lupus anticoagulant is detected, and PTI, prothrombin according to Quick, thrombin time, antithrombin III , APTT, protein C, protein S – decrease. Deviations can be detected in one or more tests, depending on which part of hemostasis is impaired. In such cases, thrombosis, thromboembolism, stages 1 and 2 of DIC syndrome are diagnosed. Also, similar changes are typical for the last trimester of pregnancy, the period after injuries, burns, and operations.

When blood clotting is insufficient (hypocoagulation), there is a risk of bleeding. In this case, the indicators of the extended coagulogram change as follows: the values ​​of PTI, prothrombin according to Quick, thrombin time, antithrombin III, APTT, protein C, protein S increase. There is no lupus anticoagulant, and the values ​​of INR, PTT, fibrinogen and D-dimer decrease. As in the previous case, a deviation can be detected in one or more analyzes. Hypocoagulation is determined by congenital or acquired deficiency of coagulation factors, including hemophilia, von Willebrand factor deficiency, hypo- and afibrinogenemia, vitamin K deficiency, stages 2 and 3 of DIC syndrome.

Treatment of abnormalities

An extended coagulogram allows a comprehensive examination of the hemostatic system, identifying deviations in various parts of the coagulation, anticoagulation and fibrinolytic systems. Its results are most in demand in hematology, surgery, obstetrics and gynecology. If deviations from the norm are detected, you must seek advice and treatment from the doctor who issued the referral for analysis. If blood clotting is increased or decreased slightly, you can correct it yourself. To do this, you need to avoid stressful situations, select physical activity in accordance with the level of fitness of the body, give up uncontrolled use of medications and smoking, and promptly identify and treat inflammatory diseases.

Coagulogram (or hemostasiogram)- a test necessary to assess the ability of blood to clot. It can indicate a pregnant woman’s tendency to form blood clots or bleeding, which helps prevent the development of pathologies of fetal formation, placental abruption and complications during childbirth.

Indications and preparation for donating blood for a coagulogram

During pregnancy, there are three scheduled blood donations for a coagulogram:

1. Immediately after registration for pregnancy.
2. Between 22-24 weeks.
3. Between 30-36 weeks.

Unscheduled blood donation for hemostasiogram is performed according to the following indications:

• long-term previous infertility;
• complications (multiple pregnancy; pregnancy resulting from IVF; as well as intrauterine growth retardation; early or late gestosis; fetoplacental insufficiency);
• varicose veins in the expectant mother;
• formation of hematomas (bruises) after minor bruises, nosebleeds, bleeding gums when brushing teeth;
• smoking and other bad habits of a pregnant woman;
• the need to assess liver function. In this case, a hemostasiogram allows you to assess the functioning of the liver by monitoring the formation of prothrombin complex factors in it;
• monitoring the state of the blood coagulation system in women who have been treated for a long time with direct anticoagulants (for example, Heparin);
• suspected blood clotting disorder.

To obtain reliable indicators of blood clotting, you need to do a hemostasiogram on an empty stomach. It is not recommended to eat food 8 hours before the test, including drinking juices, tea, coffee. Avoid eating sweets (including chewing gum with sugar). You can only drink clean water without gas.

Half an hour before donating blood, you should refrain from smoking if the expectant mother has such a bad habit. It is also not recommended to overexert yourself physically 30-40 minutes before the test. Emotionally, a woman should be calm, only slight excitement is acceptable.

Blood for analysis is taken from a vein in the crook of the arm.

Decoding coagulogram indicators

A simple hemostasiogram necessarily reveals:

• Prothrombin + INR
• Fibrinogen
• Thrombin time

An extended coagulogram is prescribed if there are deviations in a simple coagulogram or is performed immediately instead of it. Then additionally indicate:

• Antithrombin III (AT3)
• D-dimer
• Lupus anticoagulant

A referral for an extended hemostasiogram is issued according to indications. These include:

• recurrent miscarriage;
• previous long-term infertility;
• fetal death in the past;
• multiple pregnancy;
• hereditary blood diseases;
• severe forms of toxicosis (preeclampsia).

The analysis is deciphered by the attending physician in the antenatal clinic.

Norms of coagulogram indicators necessary to decipher the analysis results

Prothrombin + INR

Prothrombin(factor II) is one of the main blood clotting factors. If a deviation of this indicator from the norm is detected in a timely manner, the doctor is able to promptly prevent the development of thrombosis, placental abruption, or the occurrence of bleeding during delivery. That is why it is advisable to conduct a coagulogram in each trimester of pregnancy.

In addition, the level of prothrombin allows the doctor to assume the presence of malfunctions in the woman’s liver and digestive system. How is prothrombin connected to these organs? - you ask.

The answer is: prothrombin is produced in the liver with the participation of vitamin K. One part of this vitamin is produced by the intestinal microflora, and the other enters the body with food, which must be digested in order to obtain the coveted vitamin K.

The gastrointestinal tract and liver are involved in the digestion process, because it produces bile for gastric juice. And if the prothrombin level is reduced, it means:

1) the liver cannot cope with its duties;

2) absorption of vitamin K from the gastrointestinal tract is difficult (for example, due to diseases such as enterocolitis or ulcerative colitis);

3) the production of vitamin K does not occur completely due to disturbed intestinal microflora.

In this case, additional blood tests are prescribed for liver enzymes (ALT and AST), which are most often included in the biochemical blood test, plus directions are issued for a repeat general blood and urine test (possibly stool). If necessary, ultrasound of these organs or other diagnostic studies may be prescribed.

Modern laboratories measure prothrombin according to Quick (in %). The normal prothrombin value is in the range of 78-142%.

Some laboratories calculate only the thrombosed index (PTI). Its norm differs in different laboratories; it must be found out from the laboratory assistant.

An increased level of prothrombin (more than 142%) can be detected when:

• tendency to form blood clots. These include pre-infarction conditions and myocardial infarction, thromboembolic conditions, increased levels of globulins in the blood and hypohydration, which arose due to increased blood viscosity;
• taking medications that inhibit the effect of coumarin (for example, vitamin K) or can reduce it (meprobamate and corticosteroids).

If prothrombin is reduced (less than 78%), then the following is detected:

• hypofibrinogenemia, characterized by low levels of fibrinogen in the blood;
• lack of vitamin K in the female body (hemorrhagic diathesis in the baby);
• insufficiency of the coagulation factor prothrombin, as a result of which the pregnant woman has a tendency to bleed.

Taking anticoagulants and coumarins by the expectant mother, as well as medications that enhance their effect, also leads to a decrease in prothrombin in the blood.

INR (International Normalized Ratio) shows the rate of formation of a blood clot. An analysis to determine the level of prothrombin + INR is regularly prescribed to people who take anticoagulants - drugs that prevent thrombosis.

If the expectant mother is treated with direct anticoagulants, then the results of the coagulogram must also indicate the value of the International Normalized Ratio, which the woman must inform in advance so that an additional calculation and INR (in English INR - International Normalized Ratio) can be performed for her.

If a woman is not treated with blood thinning drugs, then the INR value is usually not indicated in the test results (it is simply not calculated, because this is not necessary).

The INR of a healthy person is within the range of 0.8-1.2. But depending on the disease and its treatment tactics, the normative range may be different. Therefore, for each patient, the norm of this indicator is determined by the attending physician and is called the “target INR range”.

If INR is below normal, then the dose of the anticoagulant is insufficient and the risk of thrombosis is still high.

If INR is higher than normal, then the selected dose of the anticoagulant is excessive and now the risk of bleeding increases.

Therefore, calculating the INR is necessary to adjust the dosage of a drug prescribed to reduce the risk of blood clots.

APTT

APTT (activated partial thromboplastin time)– the period of time during which a blood clot forms.

In the laboratory, this time is determined using the following experiment. First, the blood plasma is separated, and then reagents are added to it (calcium salt of hydrochloric acid, kaolin-kephalin mixture and others). This simulates the beginning of the natural process of blood clotting in the human body.

As a result of the experiment, the presence of factors involved in coagulation or their deficiency is established. The presence of components in the blood that slow down the coagulation process is also determined. And, of course, the very time during which a blood clot forms is recorded.

The normal APTT value for expectant mothers is in the range of 17-20 seconds.

For a non-pregnant woman, the normal APTT falls within the following time frame: 24.0 – 38.2 seconds.

APTT = 21 seconds or more. If, after adding reagents to the blood plasma, a clot has formed in more than 20 seconds, then this indicates a tendency to bleeding due to the presence of:

• second or third phase of disseminated intravascular coagulation (DIC syndrome);
• hemophilia A, B, C;
• increased production of antibodies to phospholipids.

APTT may be increased when the expectant mother is treated with heparin, therefore, in order to get a reliable result, it is necessary to stop heparin 2 days before the test or donate additional blood for lupus anticoagulant and for antibodies to cardiolipin.

APTT = 16 seconds or less. And if a clot has formed in less than 17 seconds, then this indicates:

• the initial phase of DIC syndrome, characterized by increased blood clotting, when, when injured, clots quickly form in large blood vessels, and blood clots in small ones;
• thromboembolism or thrombosis;
• increased content of activated coagulation factors;
• getting injured while taking blood for analysis (the analysis must be retaken; it is better to take blood from a vein in the second arm).

Fibrinogen

Another blood clotting factor is fibrinogen. Fibrinogen(factor I) is a special protein that is supposed to be considered the main component of a blood clot. In healthy people, it is produced by the liver and distributed throughout the circulatory system. At the site of damage to the vessel wall, fibrinogen is converted into insoluble fibrin, which becomes the basis of a blood clot. Such a blood clot clogs the damaged vessel, thereby stopping the bleeding.

Only with a sufficient number of components of the blood clot, the thrombus is stable and remains at the site of the vessel injury until healing. If there is a deficiency of factors I and II, a person is prone to increased bleeding, and if there is an excess of it, thrombosis is observed without damage (that is, pathological blood clots are formed that can break off from the walls of blood vessels and block blood flow).

Fibrinogen is measured in mg/dL or g/L. To obtain the component value in g/l, it is necessary to calculate using the formula:

mg/dl 0.01 0.555 = g/l.

Fibrinogen norm:

• until approximately 12 weeks of pregnancy – this is 2.00-4.00 g/l;
• from 3 months until the end of pregnancy, an increase in fibrin to 6.5 g/l is permissible;

The fibrinogen level should not fall below 0.5 g/l. This is a critical level of fibrinogen in the blood.

An increase in fibrinogen levels may indicate:

• the course of an acute inflammatory and infectious disease (for example, influenza);
• lack of hormones produced by the thyroid gland;
• protein metabolism disorder;
• recent surgery;
• increased estrogen content;
• extensive burn.

Low fibrinogen (less than 2.0 g/l) may result from:

• DIC syndrome;
• lack of vitamins B12 and C;
• toxicosis;
• heart failure;
• acute promyelocytic leukemia;
• complications after childbirth;
• severe liver damage;
• thrombolytic therapy.

Thrombin time

Thrombin time (TV) is the time it takes for a clot to form after mixing blood plasma with thrombin. During pregnancy, the normal TV time ranges from 10.3 to 25 seconds.

An increase in TV (more than 25 seconds) indicates:

• low fibrinogen (up to 0.5 g/l);
• liver pathologies due to the presence of fibrinogen defects at the molecular level;
• fibrinolytic therapy;
• high levels of bilirubin in the blood serum;
• the presence of direct anticoagulants in the blood during treatment with heparin or other similar drugs.

Low TV (less than 10.3 sec.) is observed when:

• high level of fibrinogen in the blood;
• the initial stage of development of DIC syndrome.

Antithrombin III

Antithrombin III (AT3)- a complex protein produced by vascular and liver cells that inhibits the process of blood clotting. It is necessary to prevent increased formation of blood clots (thrombi).

Normally, AT3 is 70-120%.

High AT3 (more than 120%) is observed with:

• acute hepatitis;
• presence of inflammation;
• cholestasis;
• severe acute pancreatitis;
• treatment with anticoagulants;
• vitamin K deficiency.

Reduced AT3 (less than 70%) may be a consequence of:

• congenital deficiency of antithrombin III;
• acute DIC syndrome;
• atherosclerosis;
• chronic liver failure;
• heparin treatment;
• blockage of a vessel by a thrombus.

D-dimer

D-dimer is an indicator that characterizes the process of thrombus formation and fibrin dissolution. Normally, by the end of pregnancy it increases 3-4 times from the initial level. But the increase in D-dimer should be gradual. Rapid growth may indicate pregnancy complications, possible kidney disease and diabetes.

D-dimer levels vary by laboratory.

For the independent laboratory "Invitro" and the clinic "Euromed" the standard values ​​for pregnant women are:

• I trimester – less than 286 ng/ml;
• II trimester – less than 457 ng/ml;
• III trimester – less than 644 ng/ml.

The D-dimer value should not fall below 33 ng/ml.

For the AltraVita clinic, the D-dimer norm during pregnancy is different:

• I trimester – from 0 to 525 ng/ml;
• II trimester – from 438 to 1200 ng/ml;
• III trimester – from 888 to 2085 ng/ml.

The Helix laboratory service has its own D-dimer standards for pregnant women:

• up to 13 weeks – 0-0.55 mcg/ml;
• 13-21 weeks – 0.2-1.4 mcg/ml;
• 21-29 weeks – 0.3-1.7 mcg/ml;
• 29-35 weeks – 0.3-3 mcg/ml;
• 35-42 weeks – 0.4-3.1 mcg/ml.

Conversion of values:

µg/ml 1000 = ng/ml

ng/ml 0.001 = µg/ml

For example, 500 ng/ml = 0.5 μg/ml.

An increase in level is observed in the presence of:

• deep vein thrombosis, pulmonary embolism;
• DIC syndrome;
• infections, sepsis;
• inflammation (with a slight increase in the D-dimer value);
• liver diseases;
• extensive hematomas.

After thrombolic therapy or surgery (even after tooth extraction), the D-dimer value may increase. Late toxicosis also contributes to an increase in this indicator.

Lupus anticoagulant

Lupus anticoagulant (LA)– antibodies that prevent the conversion of prothrombin to thrombin. Normally, during pregnancy there is no VA. The appearance of antibodies indicates autoimmune diseases (for example, systemic lupus erythematosus, antiphospholipid syndrome), when the body accepts its own cells as foreign and begins to fight them. As a rule, in the presence of VA in the blood, an increase in APTT is observed.

The standard result in seconds is 31-44 seconds.

Identification of VA occurs when:

• blockage of a vessel by a blood clot (thrombosis, thromboembolism);
• with persistent miscarriage due to antiphospholipid syndrome (APS);
• ulcerative colitis;
• rheumatoid arthritis or other autoimmune diseases;
• the presence of infectious diseases (HIV, EBV, parvovirus B19, hepatitis).

VA can be detected in human blood, but in small quantities up to 1.2 conventional units (in some laboratories up to 9 conventional units). If the lupus anticoagulant is conditionally absent, then the test results are written “negative”, if it is present in the blood - “positive”.

Treatment with anticoagulants may lead to a false-positive result, so testing for lupus anticoagulant should be performed before heparin or heparin replacement therapy.

If an extended coalogram is performed during heparin treatment, then you should not pay attention to a positive VA result.

Depending on the amount of antibodies in the sample, a comment is assigned: “weak”, “moderate” or “significant”.

General information about the study

The hemostasis system consists of many biological substances and biochemical mechanisms that ensure the preservation of the liquid state of the blood and prevent and stop bleeding. It maintains a balance between clotting and anticoagulant factors. Significant disturbances in the compensatory mechanisms of hemostasis are manifested by processes of hypercoagulation (excessive thrombus formation) or hypocoagulation (bleeding), which can threaten the patient’s life.

When tissues and blood vessels are damaged, plasma components (clotting factors) participate in a cascade of biochemical reactions, which results in the formation of a fibrin clot. There are internal and external pathways of blood coagulation, which differ in the mechanisms for triggering the coagulation process. The internal pathway is realized when blood components come into contact with the collagen of the subendothelium of the vessel wall. This process requires coagulation factors XII, XI, IX and VII. The extrinsic pathway is triggered by tissue thromboplastin (factor III) released from damaged tissue and the vascular wall. Both mechanisms are closely interrelated and from the moment of formation of active factor X they have common paths of implementation.

The coagulogram determines several important indicators of the hemostatic system. Determination of PTI (prothrombin index) and INR (international normalized ratio) allows you to assess the state of the external blood coagulation pathway. PTI is calculated as the ratio of the standard prothrombin time (the clotting time of control plasma after the addition of tissue thromboplastin) to the clotting time of the patient's plasma and is expressed as a percentage. INR is a prothrombin test standardized in accordance with international recommendations. It is calculated by the formula: INR = (patient prothrombin time / control prothrombin time) x MICH, where MICH (international sensitivity index) is the sensitivity coefficient of thromboplastin relative to the international standard. INR and PTI are inversely proportional indicators, that is, an increase in INR corresponds to a decrease in the patient’s PTI, and vice versa.

Studies of PTI (or a similar indicator - prothrombin according to Quick) and INR as part of a coagulogram help to identify disorders in the external and general blood coagulation pathways associated with a deficiency or defect of fibrinogen (factor I), prothrombin (factor II), factors V (proaccelerin) , VII (proconvertin), X (Stewart-Prower factor). With a decrease in their concentration in the blood, the prothrombin time increases in relation to control laboratory parameters.

Plasma factors of the extrinsic coagulation pathway are synthesized in the liver. For the formation of prothrombin and some other coagulation factors, vitamin K is required, the deficiency of which leads to disturbances in the cascade of reactions and prevents the formation of a blood clot. This fact is used in the treatment of patients with an increased risk of thromboembolism and cardiovascular complications. Thanks to the prescription of the indirect anticoagulant warfarin, vitamin K-dependent protein synthesis is suppressed. PTI (or Quick prothrombin) and INR coagulation are used to monitor warfarin therapy in patients with factors that promote thrombosis (for example, deep vein thrombosis, the presence of prosthetic valves, antiphospholipid syndrome).

In addition to prothrombin time and related indicators (INR, PTI, prothrombin according to Quick), other indicators of the hemostatic system can be determined in the coagulogram.

Activated partial thromboplastin time (aPTT) characterizes the intrinsic pathway of blood coagulation. The duration of APTT depends on the level of high molecular weight kininogen, prekallikrein and coagulation factors XII, XI, VIII and is less sensitive to changes in the levels of factors X, V, prothrombin and fibrinogen. APTT is determined by the duration of blood clot formation after calcium and partial thromboplastin are added to the blood sample. An increase in aPTT is associated with an increased risk of bleeding, a decrease is associated with thrombosis. This indicator is used separately to monitor therapy with direct anticoagulants (heparin).

Fibrinogen is a blood clotting factor I produced in the liver. Thanks to the action of the coagulation cascade and active plasma enzymes, it is converted into fibrin, which is involved in the formation of a blood clot and thrombus. Fibrinogen deficiency can be primary (due to genetic disorders) or secondary (due to excessive consumption in biochemical reactions), which is manifested by impaired formation of a stable blood clot and increased bleeding.

Fibrinogen is also an acute-phase protein; its concentration in the blood increases in diseases accompanied by tissue damage and inflammation. Determining the level of fibrinogen as part of a coagulogram is important in the diagnosis of diseases with increased bleeding or thrombus formation, as well as for assessing the synthetic function of the liver and the risk of cardiovascular diseases with complications.

The blood anticoagulation system prevents the formation of excess amounts of active clotting factors in the blood. Antithrombin III is the main natural inhibitor of blood clotting, which is synthesized in the liver. It inhibits thrombin, activated factors IXa, Xa and XIIa. Heparin enhances the activity of antithrombin 1000 times, being its cofactor. The proportional ratio of thrombin and antithrombin ensures the stability of the hemostatic system. With primary (congenital) or secondary (acquired) AT III deficiency, the blood coagulation process will not be stopped in a timely manner, which will lead to increased blood clotting and a high risk of thrombosis.

The formed thrombus undergoes fibrinolysis over time. D-dimer is a fibrin degradation product that allows the fibrinolytic activity of plasma to be assessed. This indicator increases significantly in conditions accompanied by intravascular thrombosis. It is also used in dynamic monitoring of the effectiveness of anticoagulant therapy.

What is the research used for?

• For a general assessment of the blood coagulation system.
• For the diagnosis of disorders of the internal, external and general pathways of blood coagulation, as well as the activity of the anticoagulant and fibrinolytic systems.
• To examine the patient before surgery.
• To diagnose the causes of miscarriage.
• For diagnosing DIC syndrome, venous thrombosis, antiphospholipid syndrome, hemophilia and assessing the effectiveness of their treatment.
• To monitor anticoagulant therapy.

When is the study scheduled?

• If DIC syndrome or pulmonary embolism is suspected.
• When planning invasive procedures (surgical interventions).
• When examining patients with nosebleeds, bleeding gums, blood in the stool or urine, hemorrhages under the skin and in large joints, chronic anemia, heavy menstrual flow, sudden loss of vision.
• When examining a patient with thrombosis, thromboembolism.
• When lupus antibodies and antibodies to cardiolipin are detected.
• With a hereditary predisposition to disorders of the hemostatic system.
• With a high risk of cardiovascular complications and thromboembolism.
• For severe liver diseases.
• With repeated miscarriages.
• When monitoring the hemostatic system against the background of long-term use of anticoagulants.

Before surgical interventions and when diagnosing various diseases, doctors refer patients for a blood test for clotting. This indicator is very important for the normal functioning of the entire body as a whole, because deviations in one direction or another pose a risk of developing serious diseases. The results of the study will tell the doctor about the abnormalities existing in the body. Let’s figure out what the normal coagulogram should be and what its main indicators tell the doctor.

Description of the analysis

A blood coagulogram is a study that shows how quickly a clot forms. It should be noted that in most cases the patient undergoes a regular coagulogram. It reports on the state of the hemostatic system, in particular the number of platelets and their aggregation, capillary resistance and bleeding time, as well as some other blood parameters. However, sometimes, to make a diagnosis, a doctor may need a detailed coagulogram, which analyzes and deciphers a number of other factors.

Each of the decoding indicators correlates with certain functions of the human body. Therefore, a deviation from the norm of the coagulogram in one direction or another will tell you which organ or system is not working correctly, and what should be given special attention. Deciphering the analysis is subject to only a specialist.

There is no need to try to diagnose yourself, because the result of treatment directly depends on the accuracy of the diagnosis.

For the convenience of analyzing the research results, a single table is created in which the obtained indicators and norms for each of them are entered. It is worth noting that the diagnosis should be made taking into account the level of all indicators entered in the table. Carrying out a blood clotting test, the norm of which depends on age, is possible only in laboratory conditions.

So, let’s take a closer look at what this analysis is and its main indicators.

Clotting time

This indicator is determined by the time interval between the moment of damage to the wall of a blood vessel (for example, a cut) and the moment the bleeding stops, which occurs due to the formation of a fibrin clot. It characterizes the efficiency of platelets. For capillary blood, the clotting time is 0.5-3 minutes, sometimes it can extend up to 5 minutes. For venous blood, this figure is normally 5-10 minutes.

An increase in the indicator above the specified norms indicates a decrease in the number of platelets, a lack of vitamin C or liver disease. It can also grow while taking contraceptives and anticoagulants.

Prothrombin index

This indicator correlates with prothrombin time (PT). PTI, like the previous indicator, is determined by the duration of blood clotting, but this process occurs when calcium and thromboplastin are added to the test sample. Thus, the ability of blood to clot with sufficient thromboplastin levels is examined.

The norms of the indicator depend on the age of the patient. For newborns, PTI is 13-18 seconds, for school-age children - 12-16 seconds, for adults 11-15 seconds.

Deviation of PTI from these norms indicates chronic liver diseases, poor intestinal absorption, and the presence of dysbacteriosis. An increase in PTI in pregnant women is considered natural and normal.

This index is directly related to the level of vitamin K in the body.

PTI evaluates the effectiveness of indirect anticoagulant therapy. If, while taking drugs, the PV increases by 1.5-2 times, then the dosage is considered sufficient.

If clotting time increases beyond normal, the risk of blood clots increases. Taking oral contraceptives can cause the same result. A very low PT indicates a risk of bleeding.

The index value is determined by the ratio of the PV of the blood plasma of a healthy person to the PV of the blood plasma of the test sample. Normally, the coagulogram PI should be 93-107%. If there are any deviations in the indicator, the patient is prescribed an additional examination.

INR

The name of this indicator is an abbreviation for International Normalized Ratio, but it is also called prothrombin ratio. It was introduced by WHO in 1983 with the aim of unifying the work of laboratories around the world, since each of them used different thromboplastins as reagents for research.

This indicator is calculated as the ratio of the patient's PT to the average prothrombin time.

It is used to monitor patients' treatment with indirect anticoagulants, such as phenylin or warfarin, which are drugs that impair blood clotting. People who are indicated for therapy with these drugs should monitor their INR at least once every three months. A decrease in INR indicates the low effectiveness of the medications taken and a possible risk of vascular thromboembolism.

An increase in this indicator can be caused by liver disease, nephrotic syndrome, hereditary disorders of clotting factors and can cause frequent bleeding.

The INR coagulogram is included in an extended study, which the doctor prescribes in addition to the main one.

APTT

This indicator is determined by the time required for the formation of a blood clot after adding special reagents to the plasma - activated partial thromboplastin time. APTT is the most accurate and sensitive element of a blood test, as it characterizes its ability to clot under the influence of plasma factors.

For a coagulogram, the normal aPTT value is 30-50 seconds. Its value changes sharply when any of the components of the coagulogram deviates from the hole by more than 30-40%. A result that is too low indicates that the blood has increased coagulability, which increases the risk of blood clots. This APTT result can be obtained if the sampling technique for a blood test is violated. Indicators above normal may be signs of hemophilia, phases 2 and 3 of disseminated intravascular coagulation syndrome (DIC), autoimmune disease, and severe liver pathology.

The APTT value increases during treatment with heparin or its analogues.

APTT is a mandatory component of a standard coagulogram.

Fibrinogen

This specific protein produced by the human liver is considered the first plasma coagulation factor. A fibrin clot, formed as a result of a series of chemical reactions, is the main component of a blood clot.

Normally, the protein concentration should be in the range of 5.9-11.7 µmol/l, which corresponds to 2-3.5 g/l. However, with liver diseases, its production decreases. Low protein levels can be caused by hereditary factors.

Protein concentration increases sharply during acute infectious diseases or inflammatory processes (pneumonia, pyelonephritis, peritonitis), with a deficiency of thyroid hormones and in the presence of malignant neoplasms. Against the background of increased coagulability, there is a risk of developing complications in the cardiovascular system.

The value of the coagulogram increases significantly during pregnancy, but this is normal, since in this way the body prepares for future blood loss. However, this indicator must be monitored once every three months throughout the entire period of gestation. Fluctuations in the direction of increasing fibrinogen concentrations in women during menstruation have been noted. In young children, normal protein coagulogram values ​​are significantly lower than in adults and amount to 1.25-3 g/l.

Dimer

The dimer is a breakdown product of fibrin, which forms a blood clot. Its quantity allows one to judge the intensity of the processes of formation and disintegration of fibrin clots.

The dimer concentration is affected not only by blood clotting, but also by the size of the clot.

Exceeding the norm indicates the presence of hematomas, venous thrombosis, vascular thromboembolism, coronary heart disease, vascular problems caused by long-term smoking, and rheumatoid arthritis.

RFMK

The amount of soluble fibrin-monomer complexes in blood plasma allows us to estimate the rate of fibrin clot breakdown under the influence of plasmin and thrombin.

To diagnose diseases, the doctor pays attention to the upper threshold of the RFMC level. Normally per 100 ml. should be 4 mg. RFMK. A higher content of complexes is fraught with the risk of intravascular thrombus formation.

An increase in the concentration of RFMK indicates the presence of:

• various thromboses,
• complications of pregnancy,
• states of shock,
• sepsis,
• renal failure,
• connective tissue pathologies.

A decrease in the concentration of RFMC is recorded during heparin administration, which makes it possible to identify patients in need of heparin therapy.

This indicator is not included in the factors of a standard examination, but is determined using a detailed coagulogram. Most often it is examined before surgery.

AVR

The activated recalcification time reflects one of the stages of blood coagulation, indicating how long it takes for fibrin to form in calcium- and platelet-rich plasma. A period of 50-70 seconds is considered a normal indicator. Exceeding the norm may indicate hemophilia, and too short a time may indicate an increased likelihood of blood clots.

Fibrinolytic activity

We got acquainted only with the most basic coagulogram indicators, which characterize the general state of the hemostatic system and allow the doctor to diagnose a number of serious internal diseases. The transcript of the analysis may contain a much larger number of parameters being studied, on the basis of which a decision will be made about the effectiveness of the therapy or the possibility of surgical intervention.

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Update: December 2018

A coagulogram (otherwise known as a hemostasiogram) is a special study that shows how well or poorly a person’s blood clotting occurs.

This analysis plays a very important role in determining a person's condition. Its indicators help predict how the operation or childbirth will go, whether the patient will survive, and whether it is possible to stop the bleeding of the wounded.

A little about blood clotting

Blood is a special liquid that has the ability not only to circulate through vessels, but also to form dense clots (thrombi). This quality allows it to close gaps in medium and small arteries and veins, sometimes even unnoticed by humans. The preservation of the liquid state and blood clotting is regulated by the hemostasis system. The coagulation system or hemostasis system consists of three components:

• vascular cells, specifically the inner layer (endothelium) - when the vessel wall is damaged or ruptured, a number of biologically active substances (nitric oxide, prostacyclin, thrombomodulin) are released from the endothelial cells, which trigger thrombus formation;
• platelets are blood platelets that are the first to rush to the site of injury. They stick together and try to close the wound (forming a primary hemostatic plug). If platelets cannot stop bleeding, plasma clotting factors are switched on;
• plasma factors– the hemostasis system includes 15 factors (many are enzymes), which, due to a series of chemical reactions, form a dense fibrin clot that finally stops bleeding.

A special feature of coagulation factors is that almost all of them are formed in the liver with the participation of vitamin K. Human hemostasis is also controlled by the anticoagulant and fibrinolytic systems. Their main function is to prevent spontaneous thrombus formation.

Indications for prescribing a hemostasiogram

How to prepare for a coagulogram?

• the material is taken strictly on an empty stomach, it is advisable that the previous meal was at least 12 hours ago;
• the day before, it is recommended not to eat spicy, fatty, smoked foods, or alcohol;
• Smoking is prohibited before collecting material;
• it is advisable to stop taking direct and indirect anticoagulants, since their presence in the blood can distort coagulogram parameters;
• if taking such medications is vital for the patient, it is necessary to warn the laboratory doctor who will review the analysis.

How is a blood clotting test performed?

• The material is collected using a dry sterile syringe or a Vacutainer vacuum blood collection system;
• Blood collection should be carried out with a wide-bore needle without using a tourniquet;
• vein puncture must be atraumatic, otherwise a lot of tissue thromboplastin will get into the tube, which will distort the results;
• the laboratory assistant fills 2 test tubes with the material, sending only the second one for examination;
• the test tube must contain a special coagulant (sodium citrate).

Where can I get tested?

This study can be carried out in any private or public clinic or laboratory that has the necessary reagents. A hemostasiogram is a difficult analysis to perform and requires sufficiently qualified laboratory technicians. The cost of the examination varies from 1000 to 3000 rubles, the price depends on the number of factors being determined.

How many days does a coagulogram take?

To obtain research results, a laboratory doctor usually carries out a series of chemical reactions that require a certain time. This usually takes 1-2 business days. One thing also depends on the workload of the laboratory, the availability of reagents, and the work of the courier.

Normal coagulogram

Decoding the coagulogram

Prothrombin time (PT)

PT is the time of formation of a thrombin clot if calcium and thromboplastin are added to the plasma. The indicator reflects phases 1 and 2 of plasma coagulation and the activity of factors 2,5,7 and 10. Norms of prothrombin time (PT) at different ages:

• Newborn premature babies – 14-19 sec;
• Newborn full-term babies - 13-17 seconds;
• Young children - 13-16 seconds;
• Older children – 12-16 seconds;
• Adults – 11-15 seconds.

Anticoagulant therapy is considered effective if the PT increases by at least 1.5-2 times.

INR

INR or prothrombin ratio is the ratio of the patient’s PV to the PV of the control tube. This indicator was introduced by the World Health Organization in 1983 to streamline the work of laboratories, since each laboratory uses different thromboplastin reagents. The main purpose of determining INR is to monitor patients’ intake of indirect anticoagulants.

Reasons for changes in PT and INR parameters:

APTT (activated partial thrombin time, cephalinkaolin time)

APTT is an indicator of the effectiveness of stopping bleeding by plasma factors. In fact, the APTT reflects the intrinsic pathway of hemostasis, how quickly a fibrin clot forms. This is the most sensitive and accurate indicator of the hemostasiogram. The APTT value primarily depends on the activator reagents used by the doctor, and the value may vary in different laboratories. A shortened APTT indicates increased coagulability and the possibility of blood clots. And its lengthening indicates a decrease in hemostasis.

Why does the APTT change?

Activated recalcification time

ABP is the time required for the formation of fibrin in plasma saturated with calcium and platelets. The indicator reflects how much the plasma and cellular components of hemostasis interact with each other. Its value may vary depending on the reagents used in the laboratory. AVR lengthens with a decrease in the number of platelets (thrombocytopenia) and a change in their quality (thrombocytopathies), hemophilia. A shortened AVR indicates a tendency to form blood clots.

Prothrombin index

The prothrombin index or PTI is the ratio of the ideal prothrombin time to the patient's prothrombin time multiplied by 100%. Currently, this indicator is considered obsolete; instead, doctors recommend determining the INR. The indicator, like the INR, levels out those differences in PT results that occur due to different thromboplastin activity in different laboratories.

Under what pathologies does the indicator change?

Thrombin time

Thrombin time shows the final stage of hemostasis. TV characterizes the length of time required for the formation of a fibrin clot in plasma if thrombin is added to it. It is always determined together with APTT and PT to monitor fibrinolytic and heparin therapy and diagnose congenital fibrinogen pathologies.

What diseases affect thrombin time?

Fibrinogen

Fibrinogen is the first blood clotting factor. This protein is produced in the liver and, under the influence of Hageman factor, is converted into insoluble fibrin. Fibrinogen is an acute phase protein; its concentration increases in plasma during infections, injuries, and stress.

Why does the level of fibrinogen in the blood change?

RFMK

SFMC (soluble fibrin-monomer complexes) are intermediate products of fibrin clot breakdown due to fibrinolysis. RFMK is very quickly eliminated from blood plasma; the indicator is very difficult to determine. Its diagnostic value lies in the early diagnosis of DIC syndrome. Also, RFMK increases with:

• thrombosis of various localizations (thromboembolism of the pulmonary artery, deep veins of the extremities);
• in the postoperative period;
• complications of pregnancy (preeclampsia, gestosis);
• acute and chronic renal failure;
• sepsis;
• shocks;
• systemic pathologies of connective tissue and others.

Antithrombin III

Antithrombin III is a physiological anticoagulant. In structure, it is a glycoprotein that inhibits thrombin and a number of coagulation factors (9,10,12). The main place of its synthesis is liver cells. Antithrombin III levels at different ages:

• Newborns – 40-80%
• Children under 10 years old – 60-100%
• Children from 10 to 16 years old – 80-120%
• Adults – 75-125%.

Why does its content in the blood change?

D-dimer

D-dimer is a remnant of fibrin filaments. This indicator reflects both the functioning of the coagulation system (if there is a lot of D-dimer in the blood, it means that a lot of fibrin has been broken down) and the function of the anticoagulant system. The indicator is contained in the blood for about 6 hours after formation, so the material must be immediately examined in the laboratory.

Only an increase in the level of the indicator, which occurs when:

• thrombosis and thromboembolism of arteries and veins;
• liver diseases;
• extensive hematomas;
• coronary heart disease and myocardial infarction;
• in the postoperative period;
• long-term smoking;
• DIC syndrome;
• seropositive rheumatoid arthritis.

Bleeding time

Method of determination: pierce the earlobe with a medical needle or scarifier. Then we note the time until the blood stops. Doctors evaluate only the lengthening of the indicator, since its shortening indicates an incorrectly conducted study. Bleeding time is prolonged due to:

• lack of platelets in the blood (thrombocytopenia);
• hemophilia A, B and C;
• liver damage by alcohol;
• hemorrhagic fevers (Crimea-Congo, with renal syndrome);
• thrombocytopenia and thrombocytopathy;
• overdose of indirect anticoagulants and anticoagulants.

Blood clotting time according to Lee-White and Mass and Magro

This test shows the time it takes for a blood clot to form. The method is very simple to perform: blood is taken from a vein. The material is poured into a dry, sterile tube. Time is recorded until a visible blood clot appears. If the hemostatic system is disrupted, the clotting time can be shortened or extended. In some pathological conditions (DIC, hemophilia), a clot may not form at all.

Coagulogram during pregnancy

During pregnancy, colossal changes occur in a woman’s body, affecting all systems, including the hemostatic system. These changes are due to the appearance of an additional circulation (uteroplacental) and changes in hormonal status (prevalence over estrogens).

During pregnancy, the activity of coagulation factors increases, especially 7,8,10 and fibrinogen. Fibrin fragments are deposited on the walls of the blood vessels of the placental-uterine system. The fibrinolysis system is suppressed. In this way, the woman’s body tries to protect itself in the event of uterine bleeding and miscarriage, and prevents placental abruption and the formation of intravascular blood clots.

Indicators of hemostasis during pregnancy

In pathological pregnancy (early and late gestosis), disturbances in the regulation of blood coagulation occur. The life of platelets is shortened and fibrinolytic activity increases. If a woman does not consult a doctor and treatment of gestosis is not carried out, a very serious complication arises - disseminated intravascular coagulation syndrome.

DIC syndrome or disseminated intravascular coagulation syndrome consists of 3 stages:

• hypercoagulability– the formation of many small blood clots, impaired blood circulation between mother and fetus;
• hypocoagulation - over time, coagulation factors are depleted in the blood, blood clots disintegrate;
• acoagulation - absence of blood clotting, uterine bleeding occurs, which threatens the life of the mother, the fetus in most cases dies.