Decrease in adf. Platelet aggregation with ADF is increased, what does this mean. Decreased platelet aggregation

Platelet aggregation is the process of platelet gluing, which is triggered by the threat of blood loss. If a vessel is damaged, the blood cells will instantly move towards the site of bleeding and begin to stick together. As a result, a blood clot forms and blocks the wound.

A low ability of platelets to agglutinate is fraught with pathological bleeding, and a high ability - the development of thrombosis and impaired blood flow. The numerical value of this indicator is determined in the laboratory.

Aggregation is not the only stage in stopping hemorrhage. This is only one component of hemostasis - a complex of physiological mechanisms that maintain the fluid state of the blood and minimize its loss when the vascular bed is damaged.

It is divided into 2 types:

• Vascular-platelet – stops hemorrhages from small vessels. For this, a microcirculatory hemostatic mechanism is sufficient.
• Coagulation – stops hemorrhages from large vessels. This requires activation of the clotting factor.

Hemostasis can be complete only if both designated mechanisms function normally and interact with each other. Then, when a vessel is damaged, a whole chain of reactions is activated, which will lead to the formation of a blood clot and blockage of the bleeding site.

It will be headed by vascular spasm. It will ensure a decrease in systolic pressure in the affected bloodstream, which will slow down blood loss.

Then the endothelial cells lining the walls of the vessel from the inside will be involved in the process. They will begin to produce anticoagulants, which will prevent the uncontrolled growth of a blood clot, and procoagulants, which will activate platelets and increase their adhesive properties. From this moment the formation of a traffic jam will begin.

Platelets will rush to the wound surface - their adhesion (adhesion to the vessel wall) and agglutination (sticking together) will begin.

At the same time, blood cells will produce:

• active substances that will increase spasm of the vessel walls, which will lead to a decrease in the speed of blood flow;
• platelet factors that will trigger the coagulation mechanism;
• thromboxane A2 and the nucleotide adenosine diphosphate (ADP) are adhesion stimulators.

The thrombus, consisting of sticky plates, will begin to grow. The platelets will continue to aggregate until the clot closes the gap in the vessel.

The resulting plug is characterized by reduced permeability to blood plasma, but is not reliable. Fibrin, an insoluble protein, will help strengthen it. Its threads will entwine platelets, compacting the glued mass - a full-fledged blood clot will form.

At the same time, the blood platelets will release the thrombostenin factor, which will tightly fix the plug. It will block the lumen in the vessel and prevent blood loss.

The destruction of the formed thrombus will be ensured by the fibrinolysis system, the main role of which is the dissolution of fibrin threads. It will also prevent excessive platelet aggregation and the formation of pathological plugs in entire vessels.

Laboratory diagnostics

To assess the aggregation activity of blood cells, a laboratory test is performed - an aggregogram.

Preparing for analysis

In order for the results of the analysis to be correct, you need to start preparing for it several weeks in advance. You cannot eat on the day on which the procedure is scheduled. You are allowed to drink only water without gases.

You must follow a diet for 3 days before blood sampling. It involves excluding garlic, coffee, turmeric, ginger, alcohol, onions and fish oil from the diet - products that affect the aggregation activity of blood cells.

For the same reason, 7 days before you need to take a clinical blood test, you will have to stop taking and using the following medications:

• beta blockers;
• calcium channel blockers;
• diuretics;
• beta-lactams;
• Aspirin;
• antimalarial drugs;
• antifungal agents;
• antidepressants;
• contraceptives;
• Dipyridamole;
• Sulfapyridazine;
• cytostatics;
• vasodilators.

During the period of preparation for the analysis, you need to stay in a calm environment, avoid physical activity and inflammatory diseases.

How is the research conducted?

The study uses an aggregometer - an automatic aggregation analyzer. It continuously records everything that happens to platelets. And then displays the recorded measurements graphically.

There are induced and spontaneous aggregation. The first is carried out with the connection of inductor substances, the second - without auxiliary activators.

Universal aggregation inducers (UAIs) are components that are similar in chemical composition to compounds that are present in human vessels and activate the process of thrombus formation. These include ADP, collagen, epinephrine (adrenaline) and arachidonic acid.

Some laboratories use compounds that are not found in the body but stimulate aggregation. For example, ristomycin (ristocetin).

Studies can be carried out simultaneously using several inducers. Such analysis can be three or five component.

The essence of the study is to pass light waves through platelet-rich plasma. The aggregation activity of blood platelets is determined by the difference between the light density of the blood before the thickening process starts and after reaching maximum aggregation.

Decoding the analysis results

Aggregation norms have two limits – the lowest and the highest:

The results may be interpreted differently in different laboratories. Therefore, you need to focus on the values ​​​​marked in the form.

Typically, the results of the aggregation diagram are entered into the form as a percentage. But sometimes they are provided in the form of a graph that shows the light transmission curve and indicates disaggregation.

A deviation from the norm to a lesser extent indicates hypoaggregation, and a greater deviation from the norm indicates hyperaggregation.

Causes and consequences of hypoaggregation

Platelet hypoaggregation can develop due to long-term use of antiplatelet agents, for example. The substance inhibits the activity of cyclooxygenase. This enzyme is necessary for the synthesis of thromboxane A2, a stimulator of platelet adhesion.

Suppression of enzyme function by aspirin persists throughout the life of the blood cell: about 10 days.

In addition to taking aspirin-containing drugs, aggregation can be inhibited by:

• aspirin-like syndrome - a defective condition against the background of a disease accompanied by a disruption in the process of platelet release for the second wave of aggregation;
• myeloproliferative disease - abnormal proliferation of bone marrow stem cells, leading to an increase in the concentration of platelets, leukocytes or red blood cells in the blood;
• hereditary diseases of the circulatory system leading to primary thrombocytopathy;
• secondary thrombocytopathies - increased bleeding, manifested by depressed platelet function, which is a complication of the underlying pathology.

The ability of platelets to clump below normal can lead to serious deterioration in health and even death. Insufficient agglutination impairs blood clotting and leads to thrombocytopenia.

Since blood clots do not form in the affected vessel, internal and external bleeding does not stop and can lead to death.

Causes and consequences of hyperaggregation

Increased platelet aggregation develops against the background of:

• thrombophilia - abnormal blood clotting, which is characterized by an increased risk of thrombosis;
• diabetes mellitus, which can cause inhibition of platelet functions and an increase in the level of coagulation factors;
• advanced atherosclerosis, which provokes a disorder of the blood clotting mechanism;
• sticky platelet syndrome - a hereditary or acquired tendency of blood platelets to increased aggregation;
• acute coronary syndrome – exacerbation of coronary heart disease, which often leads to increased aggregation;
• gestosis - a complication of pregnancy, consisting in a profound disruption of the functioning of important systems in the body;
• severe dehydration.

Platelet hyperaggregation increases the risk of thrombosis, which threatens the development of superficial or deep vein thrombosis. A detached blood clot wanders through the circulatory system and can lead to pulmonary embolism, heart attack or stroke.

Thrombosis is accompanied by bursting pain, severe weakness, swelling and pallor or cyanosis of the affected limb.

What to do if there are deviations in the analysis?

If you suspect unusual platelet aggregation activity, you should contact your physician or immediately a hematologist. The doctor will prescribe a list of additional hemostasis studies.

Treatment of hyperaggregation

The basis of treatment for excessive aggregation is the use of antithrombotic drugs and blood thinners. The latter includes aspirin. Hematologists recommend taking it in a protective coating immediately after meals to eliminate the risk of bleeding.

After a complete diagnosis, the following may be prescribed:

• anticoagulants that inhibit blood clotting - Heparin, Clexane;
• antiplatelet agents that inhibit aggregation - Aspicard, Plavix;
• inhibitors that reduce aggregation - Plestazol;
• drugs that dilate blood vessels;
• novocaine blockade;
• anesthetic drugs;
• antianginal agents (for ischemic disease).

The drug treatment regimen is developed taking into account many individual factors, so it cannot be called universal. Drugs to inhibit aggregation should be prescribed by a doctor; self-medication is fraught with aggravation of the deviation and the development of severe complications, including death.

During the treatment of hyperaggregation, you should adhere to proper nutrition. Protein foods are replaced with plant foods. The diet should be rich in herbs, garlic, oranges, grapefruits, seafood, and fresh vegetables. You will have to exclude buckwheat, pomegranate and other foods that contribute to blood thickening.

It is imperative to observe the drinking regime. The norm is 2.5 liters of water per day. Dehydration leads to vasoconstriction, causing the blood to thicken even more.

In combination with conservative therapy, traditional medicine can be used. But only after agreeing on this method of treatment with a doctor, since many medicinal herbs do not inhibit, but provoke blood clotting.

Recipes for safe folk remedies:

• Fill 1 s. l. ground clover 200 ml of boiling water and set aside for half an hour to infuse. Then divide the composition into 4 parts and drink during the day. The treatment course is 3 months.
• Grind and immerse 1 tbsp in 250 ml of alcohol. l. ground peony root and set aside to infuse for 20 days. Take the composition 30 drops 2-3 times a day.
• Mix freshly squeezed orange juice with pumpkin juice in equal proportions. Drink 100 ml of it daily.

Treatment of hypoaggregation

The medical treatment regimen (medicine regimen) for hypoaggregation necessarily includes the use of hemostatic drugs. The doctor must prescribe specific medications and determine their dosage.

There are coagulants with a direct and indirect mechanism of action. The former contain components that help blood clot. The latter are produced on the basis of vitamin K and can affect hormonal levels.

In addition to coagulants, fibrinolysis inhibitors and platelet aggregation stimulators promote blood clotting. To reduce vascular permeability, you can take ascorbic acid or Adroxon.

You should stop taking medications that have antiplatelet properties:

• Aspirin.
• Ibuprofen.
• Nimesila.
• Paracetamol.
• Troxevasin.
• Analgina.

An important element of therapy for hypoaggregation is diet. It is necessary to include in the menu products that have a beneficial effect on the hematopoietic system. These are all types of red meat, offal, fish, cheeses, eggs, pomegranates, bananas, carrots, buckwheat, sweet peppers, beets. You need to exclude ginger, garlic and citrus fruits.

You can take Piracetam, a nootropic drug that has a positive effect on metabolic processes in the brain and blood circulation.

After agreement with a hematologist, traditional methods of therapy can be used. Recipes:

• Grate fresh beets, grind with 1 tbsp. l. sugar and leave the resulting mixture overnight. In the morning, squeeze out the liquid from it and drink it on an empty stomach.
• Grind the nettles, pour in 200 ml of boiling water and heat on the stove for 10 minutes. Cool and strain the liquid. Drink it before meals.

Moderate hypo or hyperplatelet aggregation can be treated on an outpatient basis, but severe cases require hospitalization.

If you start therapy in a timely manner, the indicator will quickly return to normal. Otherwise, deviation can lead to the development of dangerous complications. Therefore, it is necessary to regularly determine the level of aggregation.

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To assess platelet function, the CIR Laboratories perform an analysis for induced platelet aggregation

Readiness of analysis results

Regular*: on the same day (subject to delivery before 12.00, in Podolsk before 11.00)

On an empty stomach, at least 8 hours after the last meal. 1 month after finishing taking the medication. drugs that affect blood clotting, unless otherwise prescribed by a doctor.

Execution Methods and Tests

Optical aggregometry. Quantitative, %

Readiness time for tests in express mode (Cito)

What is it for

• in case of miscarriage,
• unsuccessful IVF attempts,
• history of severe pregnancy complications,
• infertility of unknown origin, as well as
• with increased bleeding: easy bruising, menorrhagia, nosebleeds.

The value of tests

To assess platelet function, the CIR Laboratories perform an analysis for induced platelet aggregation. Performed on an automatic aggregometer. Since this test changes dramatically when taking drugs that affect blood clotting (antiplatelet agents, for example, Aspirin, Thrombo ACC, anticoagulants, for example, heparin), it is advisable to take it before starting to take these drugs. For each aggregogram, the laboratory doctor issues a conclusion.

The aggregation curve evaluates the amplitude of aggregation, the shape of the curve, the presence of one or two waves, and the presence of disaggregation.

The sample shown shows: 1 - zeroing of the device, 2 - before adding the inductor, 3 - peak associated with dilution of the sample by the inductor, 4 - reference point, first wave, 5 - second wave, 6 - disaggregation.

In the CIR Laboratories, platelet aggregation is performed with the following inducers:

• Aggregation with ADP;
• Aggregation with arachidonic acid;
• Aggregation with adrenaline (epinephrine);
• Aggregation with ristocetin.

The first three inducers make it possible to assess platelet function from different angles; they complement each other. Aggregation with ristocetin allows one to suspect a dangerous bleeding condition - von Willebrand disease (von Willebrand factor deficiency). When planning a pregnancy, this analysis is important to eliminate the risk of bleeding during childbirth.

Aggregation with ADP (blue wave) and arachidonic acid (black wave). The aggregation response is sharply reduced. There is virtually no disaggregation.

Aggregation with ADP.
The aggregation response is reduced. There is no disaggregation.

How to get tested at the CIR Laboratories?

To save time, place an order for analysis at Online store! Paying for your order online, you get a discount 10% for the entire placed order!

Related materials

Platelet aggregation is necessary so that when the skin is damaged, when blood vessels rupture and blood begins to be released into the external environment, the coagulation process is carried out - stopping bleeding and subsequent healing of the wound.

Without platelet aggregation, wounds would not heal because blood would flow from the damaged area without stopping. And even a small wound, if this process is disrupted, can cause a lot of problems.

Platelet aggregation - what is it?

As already noted, without platelet aggregation, blood will not clot at sites of injury. How does this process happen? First, a vessel rupture occurs.

The body understands that it is time to act. Platelets rush to the site of injury in large numbers and stick together.

When there are more clots, new platelets are added to them, attaching to the walls of the vessels. Tau and a crust forms on the scratch and wound.

That is, the role of aggregation is to “patch” the damaged vessel, stopping bleeding and providing tight conditions for the internal environment of the body. Thanks to this process, wounds heal and the person subsequently does not even remember them.

Platelet rate

In order for platelet aggregation to be normal, it is necessary to ensure that the body receives a sufficient amount of vitamins, microelements, and macroelements.

This will maintain normal hemoglobin levels in the blood when iron levels are up to standard and the blood is able to carry oxygen to organs and tissues.

When examining blood samples, the time it takes for platelets to form clots must be taken into account. The laboratory technician evaluates in real time the speed of cell movement and their transformation. The norm is from 10 seconds to one minute.

Platelet test

When should you pay attention to platelet aggregation?

1. If you notice bruises on the body, although there were no significant blows. In this case, there is a suspicion of defective platelet function.
2. If the wounds do not heal well. This means that platelets have difficulty coping with the task assigned to them - sticking together in places of damage. The result is constantly bleeding wounds that slowly close and heal.
3. If your nose bleeds frequently. Another sign of poor clotting.
4. If there is tissue swelling. This means that the aggregation rate is overestimated, which is a risk of vascular problems.

What does the analysis look like? First, the laboratory assistant takes a blood sample. Next, in laboratory conditions, an inducer (a means that allows you to trigger the natural blood clotting reaction) is introduced into the blood. At this stage, observation and measurement of belt indicators takes place.

How to prepare for the test?

1. Do not take medications without consulting your doctor. Aspirin-type drugs are prohibited because they affect platelets, make the blood thinner, and complicate clotting. The analysis result will not correspond to reality.
2. The day before the test, do not eat anything fatty. Fatty foods also affect blood clotting.
3. Do not eat anything 12 hours before your test. You can drink ordinary clean water. It is better to take the test on an empty stomach in the morning.
4. Keep calm. Remember, any anxiety can affect physical performance.
5. Do not engage in sports training in the last 24 hours before the test.
6. The day before your visit to the laboratory, you are not allowed to smoke, drink alcohol, drink coffee, or eat garlic.
7. If inflammatory processes occur, the analysis result may be incorrect. If you have a cough (sore throat), skin abscess, joint pain and the cause is inflammation, it is better to get tested later.

It is better for women not to get tested during their menstrual cycle, since during this period of time platelets are less active for natural reasons.

Changes during pregnancy

During pregnancy, women not only change their hormonal levels, but also the overall course of most processes. Poor blood clotting may also result.

Symptoms of poor aggregation during pregnancy:

1. bleeding from the nose is observed;
2. bruises appear on the body;
3. gums bleed;
4. soft tissue swelling occurs;
5. a vascular network appears (risk of developing blood clots).

Peculiarities

It is important to understand that moderate deviations from the norm are considered natural during pregnancy. Moreover, deviations can be observed in both directions - increased formation of blood clots or, on the contrary, decreased.

Why does pregnancy affect blood composition and platelet function? This is due to placental blood circulation and the peculiarities of blood supply to the extremities, when in general blood circulation becomes more complicated.

What to do if platelet aggregation is reduced?

With reduced aggregation, prolonged bleeding is observed, and the fragility of blood vessels becomes the main factor in the formation of internal bleeding, which externally manifests itself as bruises that occur without previous blows.

First, you need to avoid injury. Moreover, injuries are not only abrasions and scratches, but also blows, since when they occur without damaging the skin, the structure of the blood vessels is disrupted, they rupture and form internal bleeding.

Secondly, you need to remember that some drugs affect natural aggregation.

For example, aspirin drugs such as Indomethacin and Dipyridamole should be taken in small quantities and only when truly necessary. In some cases, they can be replaced with a more gentle alternative, depending on each specific case. Typically, aspirin drugs thin the blood, which causes poor clotting.

Also, avoid eating foods that are too salty or too spicy. Normally, such food is digested quite normally and does not harm health, but systematically taking it in excess of the norm also thins the blood and worsens aggregation.

The diet should include natural products - fruits, vegetables, milk. Apples, beets, buckwheat, meat, fish, and nuts, which have a high iron content, especially help normalize the formation and functioning of platelets.

Reasons for increased aggregation

Increased aggregation is a dangerous phenomenon that can occur in the body under favorable conditions.

The risk group is primarily hypertensive – people with diseases of the cardiovascular system.

Few people take into account that with diseases of the kidneys and stomach, problems arise with the patency of blood vessels and the blood thickens.

You also need to pay attention to nutrition - high pectin content, lack of iron, constant consumption of fatty foods are risk factors.

Increased platelet aggregation is a consequence of removal of the spleen and sepsis.

Symptoms of the disease

Thick blood that moves slowly through the vessels becomes the main symptom. How to determine if blood circulation is good? This negative factor is mainly determined by the condition of the skin. If sagging, cellulite, and pale skin appear in uncharacteristic places, the blood may be too thick and stagnant.

With increased aggregation, a feeling of numbness (especially in the fingers) and swelling appears.

Why is this dangerous?

Increased aggregation is dangerous because when it occurs, the risk of developing thrombosis, heart attack and stroke increases.

Normal for a child

Platelets in the blood of children are usually either within normal limits or elevated. The same can be said about their aggregation - the rate of “fusion” of cells can be more significant, exceeding normal limits.

Doctors calculate normal platelet levels based on the child's age, weight, and when the test was taken.

For a newborn child, the norm is 100-420 thousand. In adolescence, 75-220 thousand platelets in girls are considered normal. Aggregation speed from 10 to 40 seconds is the norm. For adolescence, aggregation of up to one minute is considered the norm.

medickon.com

Platelet aggregation: what is it, blood test, normal

Platelet aggregation, according to the logic of the name, is their union in order to stop bleeding. But this is only one, albeit important, blood clotting factor that has a numerical value.

The main function of platelets is to participate in the vascular-platelet (microcirculatory) mechanism of stopping bleeding, that is, in creating a plug (thrombus) that closes the hole in the vascular wall that appears as a result of damage. Thrombus formation occurs as a result of adhesion (sticking to the damaged vascular wall) and platelet aggregation.

As usual, for the ability of platelet aggregation, there are standards at which cell adhesion has a positive role. However, in some cases, the aggregation ability of platelets can play a negative role by disrupting the nutrition of cells of important organs due to the formation of blood clots.

What is platelet aggregation

This type of hemostasis is typical for small vessels with a small caliber and low blood pressure. Larger vessels are characterized by a coagulation mechanism, that is, activation of blood clotting.

Hemostasis system and blood clotting

Hemostasis is a complex of physiological processes in the body, thanks to which the liquid aggregate state of the blood is maintained, and blood loss is minimized when the integrity of the vascular bed is violated.

Disturbances in the functioning of this system can manifest themselves as hemorrhagic conditions (increased bleeding) or thrombotic conditions (a tendency to form small blood clots that interfere with normal blood flow due to increased platelet aggregation).

For reference. During normal functioning of the hemostatic system, damage to the vessel activates a sequential chain of events leading to the formation of a stable thrombus and cessation of bleeding. An important role in this mechanism is played by vascular spasm, which provides a decrease in blood flow at the site of injury, adhesion and aggregation of platelets, as well as activation of the coagulation cascade.

To stop bleeding in small-caliber vessels, a microcirculatory mechanism to stop bleeding is sufficient. Stopping bleeding from larger vessels is impossible without activating the blood coagulation system. However, it is necessary to understand that full maintenance of hemostasis is possible only with the normal functioning and interaction of both mechanisms.

In response to vessel damage, the following occurs:

• vascular spasm;
• release of VWF (von Willebrand factor) from damaged endothelial cells lining the vessels from the inside;
• launch of the coagulation cascade.

Endothelial cells - endothelial cells lining the inner surface of the vessel, are capable of producing anticoagulants (limiting the growth of a blood clot and controlling platelet activity) and procoagulants (activating platelets, promoting their full adhesion). These include: von Willebrand factor and tissue factor.

That is, after a spasm has occurred in response to damage to the vessel and procoagulants are released, the active process of creating a platelet plug begins. First of all, platelets begin to adhere to the damaged area of ​​the vascular bed (manifestation of adhesive properties). In parallel, they secrete biologically active substances that increase vascular spasm and reduce blood supply to the damaged area; they also secrete platelet factors that trigger the coagulation mechanism.

Among the substances secreted by platelets, it is necessary to highlight ADP and thromboxane A2, which promote active platelet aggregation, that is, adhesion to each other. Due to this, the blood clot begins to quickly increase in size. The process of platelet aggregation continues until the formed clot reaches a sufficient caliber to close the hole formed in the vessel.

In parallel with the formation of a blood clot, fibrin is released due to the work of the coagulation system. Threads of this insoluble protein tightly entwine platelets, forming a complete platelet plug (fibrin-platelet structure). Next, platelets secrete thrombosteine, which promotes contraction and tight fixation of the plug, and its transformation into a platelet thrombus. This is a temporary structure that firmly covers the damaged area of ​​the vessel and prevents blood loss.

For reference. Platelet activation decreases with distance from the damaged area of ​​the vessel. Platelets that have undergone partial activation, that is, located at the edge of the clot, are detached from it and returned to the bloodstream.

Further destruction of the formed blood clot, limiting its growth, as well as preventing the formation of small blood clots (increased platelet aggregation) in intact vessels is carried out by the fibrinolysis system.

Blood test for platelet aggregation

If it is necessary to evaluate the functional activity of platelets, an analysis with their induced aggregation is performed - an aggregogram. In essence, this study allows you to graphically display the ability of platelets to actively adhere and aggregate.

The aggregator is performed on a special automatic aggregometer. The analysis is carried out after adding aggregation stimulators to the patient's platelet-rich plasma.

Platelet aggregation inducers are divided into:

• weak (adenosine diphosphate (ADP) in small doses, adrenaline);
• strong (ADP in high doses, collagen, thrombin).

As a rule, platelet aggregation is carried out with ADP, collagen, adrenaline and ristomycin (the antibiotic ristocetin). The study of platelet activity in the presence of ristocetin is an important study in the diagnosis of hereditary hemorrhagic thrombocytopathies (von Willebrand disease and Bernard-Soulier syndrome).

In these conditions, platelet aggregation is impaired after activation by ristocetin. Under the influence of other inducers (collagen, ADP), activation occurs.

Rules for preparing for analysis

Smoking is prohibited one hour before the test. For half an hour before taking the material, the patient should be at rest.

Attention. It is important to remember that platelet activation test results change dramatically with medications that can affect blood clotting.

The attending physician and laboratory staff must be notified of the medications the patient is taking. High concentrations of anticoagulants can reduce platelet aggregation. Antiplatelet agents sharply reduce all types of activation of platelet aggregation. The use of antiplatelet agents should be stopped 10 days before the test, and non-steroidal anti-inflammatory drugs - at least three days before.

Also disrupt the aggregation ability of platelets:

• high dosages of diuretics (furosemide) and beta-lactams (penicillin, cephalosporins),
• beta blockers (propranolol),
• vasodilators,
• calcium channel blockers,
• cytostatics,
• antifungal drugs (amphotericin),
• antimalarials.

The following may also slightly reduce platelet aggregation:

• Luke,
• garlic,
• ginger,
• turmeric,
• coffee,
• fish oil.

Induced platelet aggregation. Decoding, norm and pathology

More often, the results of the study are recorded as percentages. Normal platelet aggregation with:

• ADP 5.0 µmol/ml - from sixty to ninety;
• ADP 0.5 µmol/ml – up to 1.4 to 4.3;
• adrenaline - from forty to seventy;
• collagen - from fifty to eighty;
• ristocetin - from fifty-five to one hundred.

It must be remembered that:

• activation by ristomycin is an indirect reflection of the activity of von Willebrand factor;
• ADP – platelet aggregation activity;
• collagen induction of vascular endothelial integrity.

The percentage estimate shows the degree of light transmission of the plasma after adding an aggregation inducer to it. Platelet-poor plasma is taken as light transmittance - 100%. Conversely, platelet-rich plasma is 0%.

Example: an increase in the amplitude of the light transmission curve (an increase in values ​​above normal) when adding the inducer ADP in a high dose (five µmol/ml) indicates increased aggregation activity of platelets, that is, after adding the inducer, the platelets actively stick together and the light transmission of the plasma increases.

Aggregation during pregnancy

Normal platelet aggregation during pregnancy ranges from thirty to sixty percent. In the last trimester, a slight increase in platelet aggregation may be observed.

A decrease in values ​​indicates a high risk of bleeding during childbirth, and a pronounced increase indicates a risk of thrombosis in the postpartum period, as well as possible miscarriage (threat of self-abortion).

Indications for analysis

• hemorrhagic disorders (increased bleeding);
• thrombophilia (coagulation disorder with an increased risk of thrombosis);
• severe atherosclerosis;
• diabetes mellitus;
• before performing surgical interventions;
• during pregnancy;
• when monitoring the effectiveness of anticoagulant and antiplatelet therapy.

Also, this study is important in the diagnosis of hereditary hemorrhagic thrombocytopathies.

Increased platelet aggregation. Causes

Such abnormalities in analyzes are typical for:

• thrombophilia (a coagulation disorder characterized by a tendency to form blood clots);
• DM (diabetes mellitus);
• severe atherosclerosis;
• ACS (acute coronary syndrome);
• malignant neoplasms;
• viscous platelet syndrome;
• severe dehydration (dehydration thrombophilia).

Most often, blood clots form in the deep veins of the lower extremities. The disease is manifested by bursting pain in the legs, aggravated by walking, fatigue, swelling, pallor and cyanosis of the affected limb.

Initial thrombosis primarily affects the veins of the calf muscle, then as the disease progresses, the blood clots spread higher, affecting the area of ​​the knee, thigh and pelvis. The spread of thrombosis and the increase in thrombus size increases the risk of pulmonary thromboembolism.

Reasons for the decline in aggregation

A decrease in aggregation is typical for:

• aspirin-like syndrome;
• myeloproliferative diseases;
• treatment with drugs that reduce platelet aggregation;
• uremia.

In case of von Willebrand disease (manifested by nasal, gastrointestinal, uterine bleeding, hemorrhages in muscles due to injuries, mild formation of hematomas) there will be:

• activation by ristocetin is severely impaired;
• induction of ADP, collagen and adrenaline is preserved;
• von Willebrand factor deficiency.

Bernard-Soulier syndrome (profuse bleeding from the mucous membranes of the mouth, nose, prolonged bleeding from wounds, hemorrhagic rash, extensive hematomas) is also characterized by a sharp decrease in platelet activation by ristomycin, while maintaining normal induction of ADP, etc. In this disease, von Willebrand factor activity is normal.

Glanzmann's thrombasthenia is manifested by hemorrhages in the joints, prolonged bleeding from wounds, hemorrhagic rash, and severe nosebleeds. The aggregogram shows a sharp decrease in platelet activation by ADP, adrenaline and collagen. Induction with ristomycin is not impaired.

With Wiskott-Aldrich syndrome, thrombocytopenia, eczema and frequent purulent infections are observed. The analyzes are characterized by a decrease in the reaction with collagen, adrenaline and the absence of a second wave with ADP.

serdcet.ru

Platelet aggregation in blood clotting

Platelets are small blood cells whose main function is to protect the body from internal and external bleeding. The bleeding stops due to the possibility of blood cells sticking together and the appearance of blood clots in the vessels. This is called platelet aggregation. Cells glued to each other cling to the wall of the blood vessel. Other blood elements grow on them, and all this leads to the formation of a large blood clot, which completely blocks the flow of blood into the vessel, and the bleeding stops. It is on the speed of this seemingly simple operation that human life depends.

Platelets and blood clotting

Platelet aggregation in the human body occurs only when necessary. But there are pathological cases when the unauthorized process of gluing them together can harm the body and even lead to death. We are talking about the formation of blood clots, which can cause insufficient nutrition of vital internal organs with the development of such serious diseases and conditions of the body as hemorrhagic stroke, thrombophlebitis, thrombosis of the main veins, myocardial infarction.

This is why it is important that the rate of platelet aggregation in the blood is not exceeded. This is especially important for people who have a hereditary predisposition to the formation of blood clots, or who have serious illnesses.

Norm

To determine the rate of platelet aggregation, a general blood test is performed. In this case, it is necessary to donate blood from a vein. At the time of its collection, the platelets do not receive signals from the body to stop the bleeding. In vitro - this is the name of the process of studying platelet aggregation. The name is Latin, and translated means “on glass”. The conditions in which the analysis is carried out in laboratories try to bring it as close as possible to the realities of the functioning of the human body.

To test the ability of platelets to start forming a blood clot in time and only when necessary, substances that are present in the human body are used, that is, they are not foreign to platelets - adrenaline, ristocetin, collagen. In this case, all these substances and hormones of the human body are inducers that trigger the blood cell processes necessary for laboratory research. To determine the platelet rate and pathology, the light density of blood plasma is used. The rate of platelet aggregation is calculated in the first minute of the test.

The result of the analysis depends on the blood substance that acted as an inducer. For example, with adrenaline, the normal platelet content in the blood should be between 35 and 92.5 percent.

If blood clotting during pregnancy and not only with adrenaline is reduced, there is a certain pathological process in the body that needs to be diagnosed.

For ADP (adenosine diphosphate), the normal range is considered to be 30.7 – 77.7 percent. For collagen, the normal range is 46.4 – 93.1 percent.

Preparation

If you prepare incorrectly for a blood test, its effectiveness will be in question:

• 7-10 days before donating blood, avoid taking aspirin medications and antidepressants. If it is impossible to stop taking them, you must notify the laboratory employee about this.
• At least 12 hours must pass between donating blood and the last meal. Fatty foods should be eliminated from the diet even earlier, as they cause a greater error in performance.
• A day or two before the analysis, avoid sports and do not lift weights.
• There should be no garlic in food for 24-48 hours, and drinking coffee and alcoholic beverages is prohibited. Smoking is excluded.
• If there are inflammatory processes in the body, the test is postponed until complete recovery.

Purpose

Taking a blood clotting disorder test is mandatory for patients who are prescribed medications that prevent blood from clotting. A platelet aggregation test is performed to diagnose the required dosage.

Decoding

The study of platelet aggregation is carried out using three inducers simultaneously in order to identify the main factor that activates the process of blood cell aggregation. Deviation from the norm is important for diagnosis. What does it mean if platelet aggregation with ADF is increased? It is adenosine diphosphate that influences the behavior of platelets and the initiation of their gluing process.

A decrease in platelet aggregation in the blood can be observed with properly selected drug treatment, or with the presence of diseases in the body, which are collectively called thrombocytopathy.

Etiology of thrombocytopathy

This set of diseases has a hereditary and acquired nature. According to medical statistics, about 10% of the total population of the planet have this pathology. The main characteristic of thrombocytopathy is a functional disorder of blood cells in the process of accumulation of certain blood substances.

Essentially, this is the inability of blood to clot due to the absence of a formed blood clot, which causes external and heavy internal bleeding.

The first signs of the pathological process begin to appear in childhood, and have a clinical picture of long-term non-healing wounds, large swelling at the site of minor bruises. In girls, the presence of thrombocytopathy is expressed in long-term and heavy menstruation. The result of pathology is the development of anemia.

The inactivity of blood cells to form blood clots can be caused by a severe viral or infectious disease, as well as by regular use of certain medications.

Secondary thrombocytopathy

The causes of thrombocytopathy are leukemia, pernicious anemia, and the development of myeloma. It is also observed in renal failure and disruption of the endocrine system.

Other causes of secondary thrombocytopathy:

• Atherosclerosis.
• Hypertension.
• Heart attack.
• Formation of blood clots in the arteries of the abdominal cavity.
• Stroke.
• Diabetes.

Platelet behavior during pregnancy

During pregnancy, the blood cell count may differ significantly from the norm. Manifestation: constant minor bleeding and bruising. It is imperative to warn the medical personnel who will deliver the baby about the possible risk of bleeding.

Increased platelet aggregation during pregnancy is observed mainly in the first trimester and is caused by toxicosis, during which the body loses a large amount of fluid.

If the indicator exceeds the norm, there is a risk of unwanted blood clots. The result is complications during pregnancy, including spontaneous miscarriage.

A moderate increase in the level of aggregation in a pregnant woman is the norm, and it is caused by the need to nourish the placenta with blood. Normal indicators are considered to be from 30 to 60 percent of any inductors.

A blood test to determine the degree of platelet aggregation during pregnancy is mandatory:

• With frequent pregnancies, but the inability to bear a fetus.
• With therapeutic methods of treating infertility.
• Before starting to take contraceptives, and after finishing.
• As one of the measures for diagnosing the state of the body during pregnancy planning.

A timely analysis of platelet aggregation during pregnancy allows one to predict the development of possible complications and prescribe preventive measures.

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Platelet hyperaggregation during pregnancy - what is it?

What is platelet hyperaggregation? Platelets are blood cells that take part in the process of coagulation of biological fluids. They are the main controllers of the process of stopping bleeding, as well as strengthening the walls of blood vessels. They are the ones who take part in the process of platelet aggregation and are responsible for the occurrence of such a condition as hyperaggregation. And if the first condition is quite natural for the body of a healthy person, then the second requires certain treatment.

Platelet aggregation - what is it?

It is scientifically known what the process of platelet aggregation means. It refers to the procedure of cell gluing, which results in the formation of a plug that covers the place where the wound was inflicted (no matter what size). After this, the blood cells usually adhere to the walls of the vessels and form a blood clot, which prevents heavy bleeding from developing - be it a small scratch or a large wound. However, there are points that require monitoring the ability of platelets to aggregate.

These include:

• strong blood cell activity;
• frequent and heavy bleeding.

Considering the activity of platelets, several types of their ability to aggregate are distinguished.

These include:

1. Spontaneous - no inductors are required to determine it; it is enough to place blood from a vein into a test tube heated to 37°C.
2. Induced - involves the addition of inducers of various types to the blood for a more accurate diagnosis of certain diseases. In this case, the analysis takes place in laboratory conditions.
3. Moderate - observed in women in an “interesting” position, that is, at the time of pregnancy.
4. Low - promotes heavy bleeding and requires drug intervention to prevent its consequences.
5. Increased - creates a risk of blood clots, which can lead to blockage of blood vessels and cause a stroke or heart attack.

In fact, the phenomenon of aggregation in a healthy body indicates the correct functioning of the body’s protective reaction. As a result of this process, a person is protected from large blood loss.

Platelet hyperaggregation, its causes and symptoms

The phenomenon of hyperaggregation involves an increase in the viscosity of the genetic material, which is usually characterized by its slow mobility, but rapid clotting (given the fact that the blood clotting rate is 2 minutes).

Most often, this phenomenon is observed in the case of the development of the following pathological conditions:

• with a constant increase in blood pressure;
• as a result of diabetes mellitus of various types;
• for cancer of the blood, kidneys, stomach;

• in the case of a phenomenon such as thrombocytopathy;
• with changes in blood vessels of an atherosclerotic nature.

If platelet hyperaggregation is detected during the study, we can talk about certain risks for the patient if he is not going to control the process and follow the medication prescribed by the doctor.

These risks include:

1. The occurrence of a heart attack is a disease affecting the heart muscles and characterized by circulatory failure.
2. The occurrence of a stroke is a disruption of blood circulation in the brain.
3. Blockage of veins in the legs.

State of hyperaggregation at the time of pregnancy

It is very important to monitor the phenomenon of platelet hyperaggregation during pregnancy. In this condition, it is extremely important for a woman that the test results are within reasonable indications, since not only her safety for nine months, but also labor, in which she will have to take an active part, depends on this.

The main causes of hyperaggregation during pregnancy are:

1. Severe toxicosis, characterized by constant vomiting, frequent bowel movements, leading to dehydration.
2. Pathological conditions leading to an increase in the level of platelet blood cells.

Treatment with medications in such cases is prescribed only when the special diet recommended for the pregnant woman does not help.

Experts usually advise leaning on:

• for egg and dairy products;
• for legumes;
• for cereal crops.

And yet, given that pregnancy requires a sufficient amount of vitamins and minerals for its normal development, you should not completely switch to these products. Meat and fish foods should also be present in the diet.

If you do not control these indicators, you can lose your unborn child or end up in hospital for preservation. The latter is the optimal scenario for the development of events when diagnosing hyperaggregation.

Drug effects on hyperaggregation

You should not postpone eliminating the phenomenon of hyperaggregation indefinitely. This can lead to extremely undesirable consequences. Typically, treatment of such a pathological condition involves a set of measures to eliminate it. These include both medication, prescribed even in the early stages of the process, and diet therapy, which involves the inclusion of certain foods in the diet.

As for the effects of drugs, blood thinners are most often used.

If they are ineffective, additional therapy is prescribed in the form of:

• anticoagulant agents;
• novocaine blockade;
• painkillers;
• medications that promote vasodilation.

The diet requires the mandatory inclusion of seafood, herbs, garlic, citrus fruits and ginger in the diet.

Failure to comply with the prescribed measures to influence the regulation of the body's condition can lead to serious consequences and the development of dangerous pathological conditions.

The platelet aggregation test is used before surgery and childbirth to determine the risk of bleeding. It is prescribed for vascular diseases both for the diagnosis of thrombosis, the degree of susceptibility to thrombosis, and during treatment with antiplatelet agents.

Based on the results of the analysis, it is possible to determine the effectiveness of the use of drugs for complications of atherosclerosis. ADP is used to stimulate the aggregation process; the induced reaction is important for the differential diagnosis of thrombocytopathies.

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What does a platelet aggregation test show?

The function of blood platelets is to form a blood clot at the site of damage to the vascular wall. If the vessel is in normal condition, then these cells are inactive. When a tissue defect appears, they quickly acquire the ability to adhere (adhesion) and gluing (aggregation), forming a kind of plug that clogs the vessel.

Their role is not limited to this - during bleeding, they release biologically active substances that attract other cells to the site of the “accident”, stimulate contraction of the walls of arteries and veins, and further blood clotting.

A blood test for platelet aggregation ability involves identifying their reduced, normal or increased activity during the formation of blood clots. Excessive tendency leads to blockage of arteries and veins, progression (myocardial ischemia, peripheral). Low aggregation increases the risk of bleeding.

Types of aggregation – spontaneous and ADP-induced

There are two types of platelet adhesions – spontaneous and induced. The first is determined in the blood itself, which is placed in a test tube and a thermostat that heats it to 37 degrees. Induced involves the addition of special substances that activate cell adhesion. They are called inducers, and the assay is called induced platelet aggregation. The following are used as stimulants:

• ADP - it is released by activated platelets in response to damage;
• collagen is an extracellular protein, it is discovered when the inner lining of a vessel is destroyed;
• adrenaline - found in platelet cell granules.

After adding a small amount of ADP (adenosine diphosphate, a precursor of ATP), platelets begin to join into groups and a wave appears on the screen of the device (aggregometer), it turns into a plateau (flat part), and then there is a second surge when internal aggregation factors are released from the cells. If you introduce a large dose at once, the two waves will merge into one.

Platelet bonding can be reversible or irreversible. If they have a high sensitivity to stimulation (propensity for thrombus formation), then they react to low doses (for reversible aggregation) in one wave. With low aggregation ability (there is bleeding), even high concentrations of ADP produce two waves.

Watch the video about the blood coagulation system:

Indications for when to test with ADP

A platelet aggregation test is prescribed in the following clinical situations:

• suspicion of increased bleeding (formation of hematomas on the skin, bruises, severe uterine bleeding, nasal, hemorrhoidal, gastrointestinal);
• assessment of the risk of bleeding during surgery, childbirth;
• determining the effectiveness of the use of antiplatelet agents for the prevention and treatment of thrombosis and cerebral circulatory disorders;
• determining the need for the prophylactic use of blood thinners for risk factors for myocardial ischemia (age, hypertension, diabetes mellitus, obesity, family history);
• research into the possible causes of miscarriage, missed pregnancy, infertility, unsuccessful artificial insemination;
• before starting the use of hormonal contraceptives;
• selection of drugs to prevent vascular thrombosis, identification of indications and contraindications, effective dosage, dose adjustment, risk of complications.

The ADP test is needed for the differential diagnosis of thrombocytopathies - Bernard syndrome, Wiskott syndrome, von Willebrandt disease, Glanzmann disease, as well as tumor diseases of the blood.

Preparation

An important condition for correctly determining the aggregation ability of platelets is the exclusion of possible factors that change the properties of blood. There are many drugs that distort the diagnostic result, so the doctor cancels Aspirin, Plavix, Curantil and direct anticoagulants (Warfarin, Heparin) in 7 - 10 days, and the use of anti-inflammatory drugs (Ibuprofen, Mefenamic acid) is prohibited in 3 - 5 days.

Unwanted medications also include:

• psychotropic drugs,
• anesthetics,
• Melipramine,
• Anaprilin,
• Nitroglycerine,
• Lasix,
• penicillin antibiotics,
• cephalosporins,
• Furadonin,
• Amphotericin,
• antitumor agents.

If some medications are extremely important for treatment, then in the referral for analysis, the doctor must indicate all the medications that the patient took before the analysis in the week. For 5 - 7 days, avoid taking alcohol, coffee, fish oil, ginger, turmeric, garlic and onions, vitamins C and E.

When studying platelet aggregation, the blood sample should not be cloudy due to fat, so the analysis is carried out 6 - 8 hours after the last meal, and the day before the examination there should be no fatty or fried foods on the menu.

Half an hour before the diagnosis you should not smoke; complete physical and emotional rest is required.

Analysis results

In deciphering the test for platelet aggregation, each laboratory must indicate the reference values ​​​​accepted for this diagnostic method. These are the average indicators that were found during a mass examination of healthy people. They are considered the norm.

Normal for children and adults

If there are age-related differences in the number of platelets in the blood (children have fewer of them), then for the ability to aggregate, uniform standards have been established:

• in seconds – from zero to 50 (the result may vary with different blood temperatures and research methods in a particular laboratory);
• as a percentage for spontaneous – 25 – 75;
• stimulated by ADP at a concentration of 5 µmol/ml - 60 - 89%, and at 0.5 µmol/ml - 1.4 - 4.2%.

A tendency to accelerated platelet aggregation is observed in the following diseases:

• coronary heart disease (heart attack);
• circulatory disorders in the peripheral arteries of the lower extremities (obliterating atherosclerosis);
• thromboangiitis;
• venous thrombosis;
• antiphospholipid syndrome;
• diabetes;
• congenital disorders of platelet structure;
• excessive cell formation;
• autoimmune diseases;
• in case of shock, severe toxicosis of pregnancy, placental abruption, amniotic fluid embolism, cesarean section;
• tumor processes in the body.

Smoking, high cholesterol and blood sugar levels, and stress factors can stimulate platelet aggregation. Antiplatelet agents are prescribed for treatment - Cardiomagnil, Clopidogrel, Curantil, Ipaton, Ilomedin, Agrenox, Brilinta.

Reasons for decreased

Weak spontaneous and stimulated aggregation is observed when:

• anemia;
• acute leukemia;
• renal failure;
• overdose of anticoagulants, antiplatelet agents;
• liver cirrhosis;
• diffuse glomerulonephritis;
• systemic lupus erythematosus;
• hemorrhagic vasculitis;
• angiomas;
• radiation sickness.

Congenital thrombocytopathies are accompanied by a change in the ability to aggregate (Glanzman, Pearson, May), release of cell “gluing” factors (aspirin-like syndrome), lack of storage of granules (“gray platelets”, Herzmansky syndrome), as well as various defects in heart defects, Marfan syndrome, Viskotta.

These conditions are characterized by increased bleeding, and radical elimination is not possible. Therefore, with reduced aggregation, the following diet is prescribed:

For drug therapy of congenital and acquired thrombocytopathies, Dicinone, Aminocaproic acid, and Calcium gluconate are used. A course of ATP, Riboxin and folic acid is prescribed 2 - 4 times a year. During breaks, herbal teas with hemostatic herbs are recommended - nettle, raspberry leaves, shepherd's purse, knotweed, yarrow.

The platelet aggregation test shows their ability to join together to form blood clots. Prescribed to patients before surgery, during pregnancy, as well as when prescribing treatment for thrombosis and atherosclerosis. Spontaneous and stimulated aggregation is studied. This helps to correctly diagnose and carry out therapy.

If the result is elevated, then antiplatelet agents are prescribed; if aggregation is reduced, hemostatic agents are indicated.