Norms of blood clotting in children, methods of determination and interpretation

Stroke

30182 11 August

IMPORTANT!

The information in this section cannot be used for self-diagnosis and self-treatment.
In case of pain or other exacerbation of the disease, diagnostic tests should be prescribed only by the attending physician. To make a diagnosis and properly prescribe treatment, you should contact your doctor. We remind you that independent interpretation of the results is unacceptable; the information below is for reference only.
Coagulogram (screening): indications for use, rules for preparing for the test, interpretation of the results and normal indicators.

Indications for the purpose of the study

Coagulogram (hemostasiogram) is a comprehensive hematological study aimed at assessing the state of the hemostasis system (blood clotting), or blood clotting indicators. The hemostasis system includes blood cells (platelets) and specific substances (clotting factors) dissolved in blood plasma and contained in platelets. When the integrity of the vessel wall is violated, the coagulation system is activated and a blood clot is formed, preventing blood loss.

Some time after the bleeding stops, fibrinolysis begins - the process of dissolving the blood clot after restoring the damaged vessel wall to resume blood flow.

Indications for a coagulogram are conditions accompanied by increased bleeding or, conversely, increased thrombus formation.

Increased bleeding leads to hemorrhagic syndrome. It is manifested by the formation of hematomas, pinpoint hemorrhages under the skin (petechiae), bleeding of the mucous membranes (nosebleeds, bleeding from the gums), the appearance of blood in the stool, urine, prolonged menstrual bleeding, as well as possible hemorrhages in the internal organs and body cavities. The most dangerous manifestation of hemorrhagic syndrome is hemorrhage in the brain - hemorrhagic stroke, which can lead to rapid impairment of brain function, including death. A hereditary disease associated with blood clotting disorders (decreased or absent clotting factors) is called hemophilia.

The opposite situation - thrombosis - is the formation of blood clots (thrombi) inside blood vessels, preventing the free flow of blood.

People with obesity, diabetes mellitus, heart rhythm disturbances (the most significant of which are atrial fibrillation and flutter), low physical activity, and patients after major operations (for example, joint replacement, heart valve replacement, emergency operations, etc.) are at risk of increased thrombosis. , with varicose veins, previous myocardial infarctions, strokes, and various autoimmune diseases.

Thrombosis in a certain area of ​​the vascular bed is accompanied by an acute or gradual disruption of the blood supply to any organ with disruption of its functions and subsequent tissue necrosis.

In addition to the above conditions, a coagulogram is performed before operations to assess the risk of bleeding, when prescribing certain medications, and also necessarily in case of liver diseases, since most of the proteins of the blood coagulation system are synthesized in this organ.

Fibrinogen

From all of the above, it can be understood that fibrinogen - the protein from which fibrin is formed - is extremely important for the normal process of blood clotting. The fibrinogen level for children under 14 years of age is from 2 to 4 grams per liter of blood, in infants - from 1.5 to 3 grams per liter.

A decrease in fibrinogen levels can be caused by:

• DIC syndrome;
• serious liver dysfunction; severe intoxication;
• lack of vitamins C and B;
• genetic disorders.

An increase can be caused by:

• acute infectious diseases;
• the presence of malignant tumors;
• diabetes.

Preparation for the procedure

The essence of a coagulogram is to assess the activity of proteins of the blood coagulation system.
Therefore, proper preparation for this analysis is extremely important. Blood is taken on an empty stomach; the last meal should be at least 8-10 hours before the test. It is recommended to exclude excess amounts of fatty, sweet and protein foods. The drinking regime remains normal. The day before it is necessary to avoid stressful loads and intense sports. If the patient is taking any medications that affect coagulogram parameters, then, depending on the goals set for the study, it is necessary to either continue or stop taking them a few days before. This should be discussed with your doctor before taking the test.

If you need urgent results, you can contact the INVITRO offices, where express diagnostics are carried out. In this case, the analysis will be ready in about 2 hours.

Some of the proteins of the blood coagulation system are acute phase proteins. They are produced during stress, which includes not only physical and emotional stress, but also illness. Consequently, any persistent or short-term, but intense stress in the body can lead to changes in coagulogram parameters.

Dehydration (dehydration) is one of the reasons for blood thickening and an increase in the concentration of coagulation factors, which also leads to a distortion of the result.

The state of the blood coagulation system changes during pregnancy, both in the direction of increasing and decreasing the activity of a number of proteins.

The use of many medications affects the blood coagulation system. Thus, the first generations of oral contraceptives lead to an increased risk of thrombosis, and anticoagulants lead to bleeding. The list of drugs that affect the activity of the coagulation system is huge. When receiving any drug therapy, you should first consult with your doctor about the possible effect of a particular drug on the test result.

Taking certain medications by a pregnant woman, for example, warfarin, rifampicin, phenytoin, barbiturates, affects the production of clotting factors in the fetus. The child may subsequently be at high risk of bleeding.

Antithrombin

Antithrombin III is an extremely important protein that regulates the level of blood clotting, preventing its excessive thickening and the formation of blood clots. To assess the general condition of the blood, it is necessary to know the level of antithrombin.

The content of antithrombin in the blood varies greatly depending on age: in infants it is the lowest - 60-90%, in children from one to six years old it reaches a maximum value - 101-131%, then gradually decreases, in adults reaching 66-124% .

An increase in antithrombin levels is observed when:

• acute inflammatory processes in the body;
• acute viral hepatitis;
• lack of vitamin K.

A decrease in antithrombin levels may accompany:

• liver diseases;
• DIC syndrome;
• sepsis;
• congenital disorders of antithrombin synthesis.

Coagulogram (screening)

No. OBS103Comprehensive studies

Hemostasiogram (coagulogram), screening A basic set of tests used for screening assessment of the state of the blood coagulation system.

Up to 1 business day

RUB 1,360 Add to cart

No. OBS109Comprehensive studies

Hemostasiogram (coagulogram) extended This set of tests is used for a detailed assessment of hemostasis disorders: if thrombophilia is suspected, the risk of developing thromboembolism and/or disseminated intravascular coagulation (DIC), or the patient’s severe general condition.

Up to 1 business day

RUB 3,790 Add to cart

You can take a coalogram at the nearest INVITRO medical office. A list of offices where biomaterial is accepted for laboratory research is presented in the “Addresses” section.

The blood coagulation system is primarily an enzymatic system that provides external, internal and general coagulation pathways. These mechanisms are successively replaced, but they can also occur independently of each other.

The screening coagulogram includes the following indicators:

• prothrombin (prothrombin time, prothrombin (according to Quick), INR - international normalized ratio);
• fibrinogen;
• APTT (activated partial thromboplastin time);
• thrombin time.

These indicators are basic and allow you to evaluate all coagulation pathways.

Reasons for deviation from the norm

The most common causes of changes in blood clotting parameters are disseminated intravascular coagulation syndrome, hemophilia, intoxication and acute inflammatory processes. These conditions are most often diagnosed based on the results of coagulation tests. However, we should not forget that changes in the composition of the blood can also reflect other pathological processes in the body.

The condition of the blood is influenced by many factors; it somehow “reflects” any violation of the normal state of the body. Therefore, it is necessary to pay attention to any non-standard test results, especially when it comes to the health of the child.

Normal indicators

How the analysis is carried out

A test for blood clotting in children, as in adults, is taken from a finger. The first drop is removed with a napkin, and the blood is collected in a special container. To start the reaction, the flask is slowly shaken every 30 seconds. After a certain time, you can see how the coagulation process takes place.

This method of collecting blood was proposed by Sukharev. There is another one, which is also still used, this is the Lee-White method. When using this method, blood is taken from a vein for analysis. If you donate blood in these two ways, you can get detailed information about the condition of the body.

The start and end times of coagulation are noted. It begins when the movement of blood in a test tube slows down, on average it takes from 30 to 120 seconds, and a clot forms. Over time, the sample will stop moving in the container altogether, then the coagulation process is over.

Decoding the result

I. Quick's prothrombin, prothrombin time, and international normalized ratio (INR) reflect the activity of the extrinsic coagulation pathway.

• Prothrombin time
  is the time of blood clotting after the addition of substances (thromboplastin with calcium) to the plasma that trigger the extrinsic blood coagulation pathway. Time is measured in seconds (sec.). The longer the prothrombin time, the lower the activity of coagulation factors.
• Prothrombin according to Quick
  is considered a more objective indicator of the external pathway, since during the analysis the clotting time is studied depending on the different concentration of coagulation factors in the blood obtained by diluting the test material in the laboratory. The indicator is measured as a percentage (%). The longer blood clotting occurs, the lower the Quick prothrombin percentage.
• The international normalized ratio (INR)
  is a prothrombin test standardized in accordance with international recommendations. It is calculated using a certain formula. The higher the INR, the longer it takes for a blood clot to form.

Prothrombin time, prothrombin according to Quick and INR with normal fibrinogen content and activity also reflect the activity of the prothrombin complex (II, V, VII, X blood coagulation factors).
When prescribing therapy with anticoagulants from the group of vitamin K antagonists (warfarin), there is an increase in INR and prothrombin time and a decrease in prothrombin according to Quick. Other causes of these changes may be vitamin K deficiency (for example, with hemorrhagic disease of the newborn), hereditary deficiency of factors II, V, VII, X, liver and intestinal diseases. The opposite picture, i.e., a decrease in INR, a decrease in prothrombin time and an increase in prothrombin according to Quick, occurs in conditions accompanied by increased blood clotting: thrombosis, blood thickening during dehydration, when taking oral contraceptives, barbiturates.

II. Activated partial thromboplastin time (aPTT)

with normal content and activity of fibrinogen, it characterizes the internal pathway of blood coagulation, which includes the activity of factors II, V, VIII, IX, X, XI, XII. APTT is determined by adding reagents that trigger this clotting pathway to a blood sample and measuring the time it takes for the blood to form a clot. Measured in seconds (sec.). The slower the blood clotting, the longer the APTT.

This indicator is used to monitor therapy with heparin (direct anticoagulant), and an increase in the aPTT value is noted. Other causes of increased time include hereditary and acquired deficiencies of intrinsic pathway coagulation factors, for example, in hemophilia, hemorrhagic disease of the newborn, liver and intestinal diseases, some autoimmune diseases, etc. The reasons for increased aPTT are the same as for Quick's prothrombin.

III. Thrombin time and fibrinogen reflect the overall, or final, pathway of blood clotting.

• Fibrinogen
  is blood clotting factor I, a protein synthesized in the liver and converted into fibrin, the basis of the clot during blood clotting. It is also an acute phase protein. It is measured in grams per liter (g/l). With increased thrombus formation and various inflammatory diseases, the synthesis of this protein increases. In case of liver diseases, hereditary fibrinogen deficiency, etc., its concentration decreases.
• Thrombin time
  is the blood clotting time necessary for the formation of a fibrin clot when thrombin is added to the plasma - an enzyme (factor IIa), which appears when blood coagulation factors interact when a vessel is damaged. Thrombin time depends on the level and activity of fibrinogen. Measured in seconds (sec.).

Changes in thrombin time generally correlate with fibrinogen levels. However, with such a hereditary disease as dysfibrinogenemia, i.e., a violation of the functional activity of fibrinogen, an increase in thrombin time and a coagulation disorder occurs, despite the normal amount of fibrinogen in the blood.

Bleeding time

There are many methods for studying the duration of bleeding, differing in the method of blood sampling and the method of implementation.

Currently, three methods are especially widely used:

• Ivy:
• Duke;
• Sukhareva.

The duration of bleeding according to Ivey is determined as follows: a tonometer is fixed on the patient’s shoulder, with its help a pressure of 40 mm Hg is injected. st, then a small incision is made with a blade on the inside of the forearm. After this, the time is recorded on a stopwatch, and a special filter is applied to the incision every half a minute to absorb blood. When there are no traces of blood left on the filter, the bleeding is considered to have stopped.

This method can only be used with older children and adolescents - it is considered quite aggressive.

The Duke method is more popular and is considered more gentle. To test using this method, you do not need to use a tonometer or make an incision - a small puncture of your finger or earlobe with a special Frank needle is enough. A paper filter is also applied to the puncture site, but not every half a minute, but every 15 seconds. The blood clotting rate in the Duke study does not exceed 4 minutes.

This method is used more widely and is more often used in children.

Sukharev's method is as follows: a blood sample is taken from a finger, then placed in a test tube; The tube is tilted from side to side until the blood sample begins to thicken. The norm from start to finish of coagulation is no more than 5 minutes.

Symptoms

When blood clotting time is disrupted, it may manifest itself in the following ways:

• regular bleeding, the clotting process is not complete,
• tendency to form blood clots when VSC is elevated.

Both conditions are dangerous to human life. Most often, this pathology is inherited. In this regard, a number of disorders occur in the body. Boys get bruises and nosebleeds for no reason. And girls experience heavy periods.