The activated partial thromboplastin time (aPTT) test characterizes the state of one of the three mechanisms of the hemostatic system - coagulation (blood clotting). Using the APTT analysis, all types of hemophilia are diagnosed - A, B and C, as well as hereditary, autoimmune diseases and the phases of DIC syndrome are determined.
You can take the APTT test and get reliable results with a transcript of the analysis in the Laboratory of Hemostasis Pathologies at the MLC, the base clinic of Moscow State Medical University named after. Sechenov.
When is an APTT test prescribed?
APTT is part of the blood tests for hemostasis, which are taken when planning pregnancy. The test is also prescribed for genetic predisposition to thrombosis, spontaneous bleeding of unknown origin, diagnosis of hemophilia, treatment of heart attack, during pre- and postoperative examinations.
Based on the results of the analysis, the presence of coagulation inhibitors is determined - signs of systemic lupus erythematosus and antiphospholipid syndrome, severe autoimmune pathologies. The APTT test is also used to monitor heparin therapy.
Complexes with this research
Examination during pregnancy.
3rd trimester 9,620 ₽ Composition Examination during pregnancy. 1st trimester 16,690 ₽ Composition
Extended coagulogram Extended study of the functional state of hemostasis 4,150 ₽ Composition
IN OTHER COMPLEXES
- Female infertility RUB 16,210
- Joining IVF RUB 23,020
- Pregnancy planning. Clinical indicators RUB 6,630
- Coagulogram RUB 2,020
- Miscarriage RUB 40,070
Benefits of analysis
APTT is a highly focused study that diagnoses several pathologies of hemostasis. The coagulation mechanism of hemostasis ensures the “sealing” of damage in blood vessels with fibrin clots and is influenced by blood coagulation factors.
Using the APTT test, you can detect a deficiency of the main factors affecting coagulation:
- 2nd, prothrombin;
- 5th, proaccelerin;
- 8th, antihemophilic globulin;
- 9th factor;
- 10th, Fr. Stewart-Prower;
- 11th, Dr. Rosenthal;
- 12th, Dr. Hagemann.
Coagulogram: everything you need to know about coagulation
Blood coagulation is a multi-stage, complex process and, at the same time, sensitive to the action of a number of factors. At the same time, the symptoms of “problems”, as a rule, do not make themselves felt for a long time. And clotting tests often reveal abnormalities “by chance.” So who should keep hemostasis “under supervision”? And how can those who are already undergoing treatment understand the indicators?
Who is the analysis for?
Blood clotting testing is primarily indicated for those who:
- suffers from liver disease or has had hepatitis in the past (since most clotting factors are synthesized in the liver);
- suffers from or has a hereditary predisposition to thrombophlebitis and varicose veins;
- suffers from cardiovascular or autoimmune diseases (high risk of vascular inflammation and, as a result, increased thrombosis);
- takes oral contraceptives or has excess estradiol (women);
- miscarriage in the patient’s personal history
Significant risk factors such as smoking, excess weight, sedentary lifestyle, age over 40, frequent flights and others should not be excluded from attention.
And, of course, such an analysis is mandatory before any operation, as well as for those who are already taking “anti-coagulant” drugs.
What the indicators say
The set of “standard” coagulograms (50.0.H94.203) includes the definition of:
- APTT,
- Prothrombin (time, INR),
- Thrombin time
- Fibrinogen.
But what do these indicators mean?
1. APTT, or activated partial thromboplastin time
Estimates the rate of blood clot formation after adding special reagents to plasma, and is measured in seconds.
In other words, APTT demonstrates the effectiveness of stopping bleeding due to plasma coagulation factors (precisely those that are formed in the liver).
At the same time, a lengthening (increase) of the indicator signals the risk of bleeding, and a shortening indicates thrombosis.
And the analysis is especially “relevant” for people taking direct anticoagulants (heparin and others).
2. Prothrombin time (PT)
This is the time period during which the formation of fibrin threads, that is, the actual precursor of a blood clot, occurs.
The indicator is measured as a percentage of the norm, which is 70-120%.
The higher this indicator, the higher the rate of thrombus formation, and therefore the risk of thrombosis.
A decrease in PV is a signal of a tendency to bleeding.
3. INR
In essence, it is a calculated indicator designed to standardize data on prothrombin time obtained using different equipment.
Such “difficulties” have become necessary due to the fact that INR is the basic analysis for the selection and correction of “anticoagulant” drugs (such as warfarin). And data obtained on different equipment (in different laboratories) often did not allow comparison with each other.
Therefore, the International Committee for Standardization in Hematology and the International Committee on Thrombosis and Haemostasis introduced the use of INR in 1983.
And today, its level for a healthy person is at the level of 0.8-1.2. And for those taking indirect anticoagulants – 2.0-4.0.
At the same time, an increase in INR is associated with the risk of bleeding, and a decrease of less than 0.5 may indicate thrombosis.
4. Fibrinogen
Unlike previous indicators, this is directly a substrate for the formation of a blood clot. That is, not an indicator of speed, but a substance. Therefore, the norms for fibrinogen are measured in grams per liter.
An increase in fibrinogen is observed not only with increased thrombus formation, but also with many inflammatory processes (as a way for the body to limit the spread of the “causal factor” and destroyed tissues). And also for those who take oral contraceptives or have elevated estrogen levels, pregnant women, people with high cholesterol and smokers.
A decrease in the indicator can indicate not only the risk of bleeding, but also liver disease.
Of course, the listed indicators are only a “base” for assessing the “health” of the blood coagulation system. And if significant deviations are detected, additional markers may be needed.
Decoding
The standard for the test is 24-35 seconds. Physiological changes in hemostasis occur in the body of expectant mothers, so the APTT during pregnancy is reduced to 17-20 seconds. The type of pathology is determined based on the shortening or lengthening of the APTT.
What does it mean if APTT is higher than normal?
Prolongation of APTT is a sign of deficiency of blood coagulation factors: 8th in hemophilia A, 9th in hemophilia B, 11th in hemophilia C, as well as von Willebrand disease - an inherited tendency to spontaneous bleeding.
If the marker increases, additional tests are performed for lupus anticoagulant and antiphospholipid syndrome, and if the patient receives heparin injections, the dose of the drug is adjusted.
What does it mean if APTT is below normal?
A shortening of the activated partial thromboplastin time indicates the risk of developing thrombosis - blockage of blood vessels, or thromboembolism - a blood clot breaking off and entering the circulating blood. Low aPTT determines the first phase of disseminated intravascular coagulation.
If venous blood is collected incorrectly or the sample is contaminated, a decrease in the marker is also observed - in such cases, the analysis is repeated.
Activated partial thromboplastin time, or aPTT, is the time it takes for a blood clot to form after calcium chloride and other reagents are added to the plasma. It reflects the work of the so-called internal pathway and the general cascade of the human blood coagulation system and is the most sensitive indicator of blood coagulation.
Synonyms Russian
Activated partial thromboplastin time, cephalin-kaolin time.
English synonyms
Partial Thromboplastin Time (PTT), Activated Partial Thromboplastin Time, aPTT, APTT.
Research method
Side scatter detection method, end point percentage determination.
Units
Sec. (second).
What biomaterial can be used for research?
Venous blood.
How to properly prepare for research?
- Do not eat for 12 hours before the test.
- Avoid physical and emotional stress 30 minutes before the test.
- Do not smoke for 30 minutes before the test.
General information about the study
Activated partial thromboplastin time (aPTT) characterizes the intrinsic pathway of blood coagulation. APTT is the time it takes for a clot to form in a blood plasma sample after adding special activators of this process. In this way, the degree of influence of blood clotting factors on the formation of a blood clot is assessed.
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 amount 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 duration is associated with an increased risk of bleeding, while a decrease is associated with thrombosis. This indicator is used separately to monitor therapy with direct anticoagulants (heparin).
What is the research used for?
- For the diagnosis of hemophilia.
- To monitor heparin anticoagulant therapy.
- For the diagnosis of deep hypofibrinogenemia, dysfibrinogenemia and disorders of fibrin monomer polymerization.
- To determine the patient’s predisposition to bleeding (as part of preoperative procedures).
When is the study scheduled?
- If the patient has bleeding or bruising of unknown origin, thromboembolism or disseminated intravascular coagulation, which can cause both bleeding and blood clots.
- When carrying out heparin therapy or when transferring a patient from heparin therapy to long-term treatment with warfarin.
- As part of a preoperative examination to identify the body's tendency to bleed, especially if the proposed operation is associated with a large loss of blood or the patient's clinical history indicates earlier bleeding.
- In the treatment of myocardial infarction.
What do the results mean?
Reference values: 21.1 - 36.5 sec.
An increase in aPTT indicates a tendency to bleed: blood clotting lasts longer than usual, which often indicates a deficiency in one of the coagulation factors or the effect of some inhibitor on the body's ability to form clots.
What can influence the result?
- The presence of impurities of direct anticoagulants (in particular, heparin) in the blood sample
- High concentration of lipids (fats) in the blood, for example, after eating a fatty meal the night before the test
Where to get tested for APTT in Moscow
You can take an APTT test and get advice from an experienced hemostasiologist at the Women's Medical Center on Zemlyanoy Val. Our Hemostasis Pathology Laboratory has high-precision blood analyzers, high-quality reagents and consumables, which guarantees the reliability of the research results.
Along with the APTT test, you have the opportunity to take tests close to it: 2-TEG, extended hemostasiogram, tests for VA and APS, Antithrombin, and also determine the anti-Xa activity of heparin in the blood. In the experimental laboratory of the MLC, we are engaged not only in diagnostics: we research and practice new methods for treating hematological diseases.
In one of the private laboratories you are another statistical unit, but with us you are a patient who is ready to be helped by the best doctors in Moscow.
Activated Partial Thromboplastin Time
APTT is one of the most sensitive indicators of the hemocoagulation system, which reflects the state of the internal pathway and the general cascade of the blood coagulation system. This test is used for screening assessment of the blood coagulation system, as well as to determine hypocoagulation changes and to monitor the use of anticoagulants.
Activated partial thromboplastin time
- an indicator that is one of the basic tests for assessing blood clotting. It is prescribed during the diagnosis of hemophilia, deep hypofibrinogenemia, dysfibrinogenemia. For patients undergoing heparin anticoagulant therapy, the analysis is carried out at regular intervals to prevent overdose. If surgery is planned, this test is included in the preoperative examination to determine the risk of significant blood loss, take action if necessary and prevent a threat to life.
The clotting mechanism is activated when bleeding occurs. It serves as a natural protection against excess blood loss. The resulting blood clot covers the damage to the vessel or tissue, first slows down the bleeding, and then completely stops it. After healing, the clot dissolves. Normally, a blood clot forms only when blood vessels or tissues are damaged, but in a number of pathologies they can form inside a vessel. In hemophilia, the coagulation mechanism is also impaired. This is a hereditary disease that is rare. The disease is hereditary and is associated with gene mutations. To diagnose it, a comprehensive examination is carried out. Today the disease is incurable, but its course is successfully controlled. In children with this diagnosis, increased bleeding is observed from the first days of life. The disease affects males.
According to the results of APTT analysis
it is possible to judge the impact of clotting factors on the thrombus formation system. If the aPTT is higher than normal, it means that the clot is taking too long to form, which may indicate a clotting factor deficiency. That is, the body is not able to stop bleeding in a timely manner in case of injury or during surgery.
It must be taken into account that when heparin is used in large doses, the formation of blood clots is significantly reduced. The drug is used in large doses, for example, during open heart surgery. In such situations, this analysis is not prescribed, since its sensitivity will be low. Test results may be affected by high concentrations of lipids in the blood. Therefore, on the eve of collecting biomaterial, it is recommended to refrain from eating large amounts of fatty foods. During preventive examinations, an aPTT test is usually not prescribed. It is performed on patients with a hereditary predisposition to hemophilia or thrombosis. The analysis is also often included in a comprehensive examination before surgery. Based on its results, the doctor assesses the risk of severe bleeding and significant blood loss during surgery. The need for this test is determined by your doctor. The test is not intended for self-diagnosis.
